diff --git a/app/Api/V1/Requests/Models/Transaction/UpdateRequest.php b/app/Api/V1/Requests/Models/Transaction/UpdateRequest.php
index 9cbe848241..adaa967a62 100644
--- a/app/Api/V1/Requests/Models/Transaction/UpdateRequest.php
+++ b/app/Api/V1/Requests/Models/Transaction/UpdateRequest.php
@@ -85,7 +85,7 @@ class UpdateRequest extends FormRequest
             'notes',
         ];
 
-        $this->floatFields = [
+        $this->floatFields = [ // not really floats, for validation.
             'amount',
             'foreign_amount',
         ];
@@ -406,8 +406,7 @@ class UpdateRequest extends FormRequest
             if (array_key_exists($fieldName, $transaction)) {
                 $value = $transaction[$fieldName];
                 if (is_float($value)) {
-                    // TODO this effectively limits the max number of decimals in currencies to 14.
-                    $current[$fieldName] = sprintf('%.14f', $value);
+                    $current[$fieldName] = sprintf('%.24f', $value);
                 }
                 if (!is_float($value)) {
                     $current[$fieldName] = (string) $value;
diff --git a/app/Api/V1/Requests/User/PreferenceStoreRequest.php b/app/Api/V1/Requests/User/PreferenceStoreRequest.php
index c626ccdfa5..39d6b575ee 100644
--- a/app/Api/V1/Requests/User/PreferenceStoreRequest.php
+++ b/app/Api/V1/Requests/User/PreferenceStoreRequest.php
@@ -46,9 +46,8 @@ class PreferenceStoreRequest extends FormRequest
         if ('false' === $array['data']) {
             $array['data'] = false;
         }
-        // TODO remove float
         if (is_numeric($array['data'])) {
-            $array['data'] = (float) $array['data'];
+            $array['data'] = (float) $array['data']; // intentional float.
         }
 
         return $array;
diff --git a/app/Api/V1/Requests/User/PreferenceUpdateRequest.php b/app/Api/V1/Requests/User/PreferenceUpdateRequest.php
index 9a40f689c7..a115bfba0a 100644
--- a/app/Api/V1/Requests/User/PreferenceUpdateRequest.php
+++ b/app/Api/V1/Requests/User/PreferenceUpdateRequest.php
@@ -47,9 +47,8 @@ class PreferenceUpdateRequest extends FormRequest
         if ('false' === $array['data']) {
             $array['data'] = false;
         }
-        // TODO remove float
         if (is_numeric($array['data'])) {
-            $array['data'] = (float) $array['data'];
+            $array['data'] = (float) $array['data']; // intentional float.
         }
 
         return $array;
diff --git a/app/Http/Controllers/Report/TagController.php b/app/Http/Controllers/Report/TagController.php
index bf263bb2a5..e83a3c25b1 100644
--- a/app/Http/Controllers/Report/TagController.php
+++ b/app/Http/Controllers/Report/TagController.php
@@ -542,7 +542,7 @@ class TagController extends Controller
                     $result[] = [
                         'description'             => $journal['description'],
                         'transaction_group_id'    => $journal['transaction_group_id'],
-                        'amount_float'            => (float) $journal['amount'],
+                        'amount_float'            => (float) $journal['amount'], // intentional float.
                         'amount'                  => $journal['amount'],
                         'date'                    => $journal['date']->isoFormat($this->monthAndDayFormat),
                         'date_sort'               => $journal['date']->format('Y-m-d'),
diff --git a/app/Http/Requests/RecurrenceFormRequest.php b/app/Http/Requests/RecurrenceFormRequest.php
index 41e5c010ab..c90ee927ae 100644
--- a/app/Http/Requests/RecurrenceFormRequest.php
+++ b/app/Http/Requests/RecurrenceFormRequest.php
@@ -99,7 +99,7 @@ class RecurrenceFormRequest extends FormRequest
         ];
 
         // fill in foreign currency data
-        if (null !== $this->convertFloat('foreign_amount')) {
+        if (null !== $this->convertFloat('foreign_amount')) { // intentional float, used because it defaults to null.
             $return['transactions'][0]['foreign_amount']      = $this->convertString('foreign_amount');
             $return['transactions'][0]['foreign_currency_id'] = $this->convertInteger('foreign_currency_id');
         }
@@ -228,7 +228,7 @@ class RecurrenceFormRequest extends FormRequest
             $rules['repetitions'] = 'required|numeric|between:0,254';
         }
         // if foreign amount, currency must be  different.
-        if (null !== $this->convertFloat('foreign_amount')) {
+        if (null !== $this->convertFloat('foreign_amount')) { // intentional float, used because it defaults to null.
             $rules['foreign_currency_id'] = 'exists:transaction_currencies,id|different:transaction_currency_id';
         }
 
diff --git a/app/Support/Amount.php b/app/Support/Amount.php
index 4f2d120f2a..6ed95c2833 100644
--- a/app/Support/Amount.php
+++ b/app/Support/Amount.php
@@ -71,8 +71,8 @@ class Amount
      */
     public function formatFlat(string $symbol, int $decimalPlaces, string $amount, bool $coloured = null): string
     {
-        $locale = app('steam')->getLocale();
-        $rounded = app('steam')->bcround($amount, $decimalPlaces);
+        $locale   = app('steam')->getLocale();
+        $rounded  = app('steam')->bcround($amount, $decimalPlaces);
         $coloured = $coloured ?? true;
 
         $fmt = new NumberFormatter($locale, NumberFormatter::CURRENCY);
diff --git a/app/Support/Chart/Category/FrontpageChartGenerator.php b/app/Support/Chart/Category/FrontpageChartGenerator.php
index d12cf4c633..ad397bff9c 100644
--- a/app/Support/Chart/Category/FrontpageChartGenerator.php
+++ b/app/Support/Chart/Category/FrontpageChartGenerator.php
@@ -152,7 +152,7 @@ class FrontpageChartGenerator
             $tempData[] = [
                 'name'        => trans('firefly.no_category'),
                 'sum'         => $currency['sum'],
-                'sum_float'   => round((float) $currency['sum'], $currency['currency_decimal_places'] ?? 2),
+                'sum_float'   => round((float) $currency['sum'], $currency['currency_decimal_places'] ?? 2), // intentional float
                 'currency_id' => (int) $currency['currency_id'],
             ];
         }
diff --git a/app/Support/Http/Controllers/ModelInformation.php b/app/Support/Http/Controllers/ModelInformation.php
index 9164a6098f..621dd26b84 100644
--- a/app/Support/Http/Controllers/ModelInformation.php
+++ b/app/Support/Http/Controllers/ModelInformation.php
@@ -130,8 +130,8 @@ trait ModelInformation
         $billTriggers = ['currency_is', 'amount_more', 'amount_less', 'description_contains'];
         $values       = [
             $bill->transactionCurrency()->first()->name,
-            round((float) $bill->amount_min, 24),
-            round((float) $bill->amount_max, 24),
+            $bill->amount_min,
+            $bill->amount_max,
             $bill->name,
         ];
         foreach ($billTriggers as $index => $trigger) {
diff --git a/app/Support/Steam.php b/app/Support/Steam.php
index 4f31bf42b0..cf2f38f53b 100644
--- a/app/Support/Steam.php
+++ b/app/Support/Steam.php
@@ -590,8 +590,10 @@ class Steam
             if ($mantis < 0) {
                 $post += abs((int)$mantis);
             }
+            // TODO careless float could break financial math.
             return number_format((float)$value, $post, '.', '');
         }
+        // TODO careless float could break financial math.
         return number_format((float)$value, 0, '.', '');
     }
 
diff --git a/app/Transformers/AccountTransformer.php b/app/Transformers/AccountTransformer.php
index 19649aaedb..87bcd35a6a 100644
--- a/app/Transformers/AccountTransformer.php
+++ b/app/Transformers/AccountTransformer.php
@@ -76,7 +76,7 @@ class AccountTransformer extends AbstractTransformer
         [$openingBalance, $openingBalanceDate] = $this->getOpeningBalance($account, $accountType);
         [$interest, $interestPeriod] = $this->getInterest($account, $accountType);
 
-        $openingBalance  = number_format((float) $openingBalance, $decimalPlaces, '.', '');
+        $openingBalance  = app('steam')->bcround($openingBalance, $decimalPlaces);
         $includeNetWorth = '0' !== $this->repository->getMetaValue($account, 'include_net_worth');
         $longitude       = null;
         $latitude        = null;
@@ -107,7 +107,7 @@ class AccountTransformer extends AbstractTransformer
             'currency_code'           => $currencyCode,
             'currency_symbol'         => $currencySymbol,
             'currency_decimal_places' => $decimalPlaces,
-            'current_balance'         => number_format((float) app('steam')->balance($account, $date), $decimalPlaces, '.', ''),
+            'current_balance'         => app('steam')->bcround(app('steam')->balance($account, $date), $decimalPlaces),
             'current_balance_date'    => $date->toAtomString(),
             'notes'                   => $this->repository->getNoteText($account),
             'monthly_payment_date'    => $monthlyPaymentDate,
@@ -115,7 +115,7 @@ class AccountTransformer extends AbstractTransformer
             'account_number'          => $this->repository->getMetaValue($account, 'account_number'),
             'iban'                    => '' === $account->iban ? null : $account->iban,
             'bic'                     => $this->repository->getMetaValue($account, 'BIC'),
-            'virtual_balance'         => number_format((float) $account->virtual_balance, $decimalPlaces, '.', ''),
+            'virtual_balance'         => app('steam')->bcround($account->virtual_balance, $decimalPlaces),
             'opening_balance'         => $openingBalance,
             'opening_balance_date'    => $openingBalanceDate,
             'liability_type'          => $liabilityType,
diff --git a/app/Transformers/AvailableBudgetTransformer.php b/app/Transformers/AvailableBudgetTransformer.php
index b9fd050673..62944bab86 100644
--- a/app/Transformers/AvailableBudgetTransformer.php
+++ b/app/Transformers/AvailableBudgetTransformer.php
@@ -69,7 +69,7 @@ class AvailableBudgetTransformer extends AbstractTransformer
             'currency_code'           => $currency->code,
             'currency_symbol'         => $currency->symbol,
             'currency_decimal_places' => (int) $currency->decimal_places,
-            'amount'                  => number_format((float) $availableBudget->amount, $currency->decimal_places, '.', ''),
+            'amount'                  => app('steam')->bcround($availableBudget->amount, $currency->decimal_places),
             'start'                   => $availableBudget->start_date->toAtomString(),
             'end'                     => $availableBudget->end_date->endOfDay()->toAtomString(),
             'spent_in_budgets'        => [],
diff --git a/app/Transformers/BillTransformer.php b/app/Transformers/BillTransformer.php
index 9885840f30..8b6ec658be 100644
--- a/app/Transformers/BillTransformer.php
+++ b/app/Transformers/BillTransformer.php
@@ -115,8 +115,8 @@ class BillTransformer extends AbstractTransformer
             'currency_symbol'          => $currency->symbol,
             'currency_decimal_places'  => (int) $currency->decimal_places,
             'name'                     => $bill->name,
-            'amount_min'               => number_format((float) $bill->amount_min, $currency->decimal_places, '.', ''),
-            'amount_max'               => number_format((float) $bill->amount_max, $currency->decimal_places, '.', ''),
+            'amount_min'               => app('steam')->bcround($bill->amount_min, $currency->decimal_places),
+            'amount_max'               => app('steam')->bcround($bill->amount_max, $currency->decimal_places),
             'date'                     => $bill->date->toAtomString(),
             'end_date'                 => $bill->end_date?->toAtomString(),
             'extension_date'           => $bill->extension_date?->toAtomString(),
diff --git a/app/Transformers/BudgetLimitTransformer.php b/app/Transformers/BudgetLimitTransformer.php
index efea0b5d7f..26570b4e6b 100644
--- a/app/Transformers/BudgetLimitTransformer.php
+++ b/app/Transformers/BudgetLimitTransformer.php
@@ -80,7 +80,7 @@ class BudgetLimitTransformer extends AbstractTransformer
             $currencySymbol        = $currency->symbol;
             $currencyDecimalPlaces = $currency->decimal_places;
         }
-        $amount = number_format((float) $amount, $currencyDecimalPlaces, '.', '');
+        $amount = app('steam')->bcround($amount, $currencyDecimalPlaces);
 
         return [
             'id'                      => (string) $budgetLimit->id,
diff --git a/app/Transformers/BudgetTransformer.php b/app/Transformers/BudgetTransformer.php
index 3f5cf67e95..ef76034750 100644
--- a/app/Transformers/BudgetTransformer.php
+++ b/app/Transformers/BudgetTransformer.php
@@ -84,7 +84,7 @@ class BudgetTransformer extends AbstractTransformer
             $abCurrencyId   = (string) $autoBudget->transactionCurrency->id;
             $abCurrencyCode = $autoBudget->transactionCurrency->code;
             $abType         = $types[$autoBudget->auto_budget_type];
-            $abAmount       = number_format((float) $autoBudget->amount, $autoBudget->transactionCurrency->decimal_places, '.', '');
+            $abAmount       = app('steam')->bcround($autoBudget->amount, $autoBudget->transactionCurrency->decimal_places);
             $abPeriod       = $autoBudget->period;
         }
 
@@ -120,7 +120,7 @@ class BudgetTransformer extends AbstractTransformer
     {
         $return = [];
         foreach ($array as $data) {
-            $data['sum'] = number_format((float) $data['sum'], (int) $data['currency_decimal_places'], '.', '');
+            $data['sum'] = app('steam')->bcround($data['sum'], (int) $data['currency_decimal_places']);
             $return[]    = $data;
         }
 
diff --git a/app/Transformers/CategoryTransformer.php b/app/Transformers/CategoryTransformer.php
index 295b30fa01..81fe257bf8 100644
--- a/app/Transformers/CategoryTransformer.php
+++ b/app/Transformers/CategoryTransformer.php
@@ -95,7 +95,7 @@ class CategoryTransformer extends AbstractTransformer
     {
         $return = [];
         foreach ($array as $data) {
-            $data['sum'] = number_format((float) $data['sum'], (int) $data['currency_decimal_places'], '.', '');
+            $data['sum'] = app('steam')->bcround($data['sum'], (int) $data['currency_decimal_places']);
             $return[]    = $data;
         }
 
diff --git a/app/Transformers/PiggyBankEventTransformer.php b/app/Transformers/PiggyBankEventTransformer.php
index 80da4595c1..37e7d60fbd 100644
--- a/app/Transformers/PiggyBankEventTransformer.php
+++ b/app/Transformers/PiggyBankEventTransformer.php
@@ -83,7 +83,7 @@ class PiggyBankEventTransformer extends AbstractTransformer
             'id'                      => (string) $event->id,
             'created_at'              => $event->created_at->toAtomString(),
             'updated_at'              => $event->updated_at->toAtomString(),
-            'amount'                  => number_format((float) $event->amount, $currency->decimal_places, '.', ''),
+            'amount'                  => app('steam')->bcround($event->amount, $currency->decimal_places),
             'currency_id'             => (string) $currency->id,
             'currency_code'           => $currency->code,
             'currency_symbol'         => $currency->symbol,
diff --git a/app/Transformers/PiggyBankTransformer.php b/app/Transformers/PiggyBankTransformer.php
index 7a66774b43..aca43a7a69 100644
--- a/app/Transformers/PiggyBankTransformer.php
+++ b/app/Transformers/PiggyBankTransformer.php
@@ -53,7 +53,7 @@ class PiggyBankTransformer extends AbstractTransformer
     /**
      * Transform the piggy bank.
      *
-     * @param PiggyBank $piggyBank
+     * @param  PiggyBank  $piggyBank
      *
      * @return array
      * @throws \FireflyIII\Exceptions\FireflyException
@@ -81,44 +81,44 @@ class PiggyBankTransformer extends AbstractTransformer
         /** @var ObjectGroup $objectGroup */
         $objectGroup = $piggyBank->objectGroups->first();
         if (null !== $objectGroup) {
-            $objectGroupId    = (int) $objectGroup->id;
-            $objectGroupOrder = (int) $objectGroup->order;
+            $objectGroupId    = (int)$objectGroup->id;
+            $objectGroupOrder = (int)$objectGroup->order;
             $objectGroupTitle = $objectGroup->title;
         }
 
         // get currently saved amount:
         $currentAmountStr = $this->piggyRepos->getCurrentAmount($piggyBank);
-        $currentAmount    = number_format((float) $currentAmountStr, $currency->decimal_places, '.', '');
+        $currentAmount    = app('steam')->bcround($currentAmountStr, $currency->decimal_places);
 
         // Amounts, depending on 0.0 state of target amount
         $percentage         = null;
         $targetAmountString = null;
         $leftToSaveString   = null;
         $savePerMonth       = null;
-        if (0.000 !== (float) $piggyBank->targetamount) {
+        if (0 !== bccomp(app('steam')->bcround($currentAmountStr, $currency->decimal_places), '0')) {
             $leftToSave         = bcsub($piggyBank->targetamount, $currentAmountStr);
-            $targetAmount       = (string) $piggyBank->targetamount;
+            $targetAmount       = (string)$piggyBank->targetamount;
             $targetAmount       = 1 === bccomp('0.01', $targetAmount) ? '0.01' : $targetAmount;
-            $percentage         = (int) (0 !== bccomp('0', $currentAmountStr) ? $currentAmountStr / $targetAmount * 100 : 0);
-            $targetAmountString = number_format((float) $targetAmount, $currency->decimal_places, '.', '');
-            $leftToSaveString   = number_format((float) $leftToSave, $currency->decimal_places, '.', '');
-            $savePerMonth       = number_format((float) $this->piggyRepos->getSuggestedMonthlyAmount($piggyBank), $currency->decimal_places, '.', '');
+            $percentage         = (int)(0 !== bccomp('0', $currentAmountStr) ? $currentAmountStr / $targetAmount * 100 : 0);
+            $targetAmountString = app('steam')->bcround($targetAmount, $currency->decimal_places);
+            $leftToSaveString   = app('steam')->bcround($leftToSave, $currency->decimal_places);
+            $savePerMonth       = app('steam')->bcround($this->piggyRepos->getSuggestedMonthlyAmount($piggyBank), $currency->decimal_places);
         }
         $startDate  = $piggyBank->startdate?->toAtomString();
         $targetDate = $piggyBank->targetdate?->toAtomString();
 
 
         return [
-            'id'                      => (string) $piggyBank->id,
+            'id'                      => (string)$piggyBank->id,
             'created_at'              => $piggyBank->created_at->toAtomString(),
             'updated_at'              => $piggyBank->updated_at->toAtomString(),
-            'account_id'              => (string) $piggyBank->account_id,
+            'account_id'              => (string)$piggyBank->account_id,
             'account_name'            => $piggyBank->account->name,
             'name'                    => $piggyBank->name,
-            'currency_id'             => (string) $currency->id,
+            'currency_id'             => (string)$currency->id,
             'currency_code'           => $currency->code,
             'currency_symbol'         => $currency->symbol,
-            'currency_decimal_places' => (int) $currency->decimal_places,
+            'currency_decimal_places' => (int)$currency->decimal_places,
             'target_amount'           => $targetAmountString,
             'percentage'              => $percentage,
             'current_amount'          => $currentAmount,
@@ -126,16 +126,16 @@ class PiggyBankTransformer extends AbstractTransformer
             'save_per_month'          => $savePerMonth,
             'start_date'              => $startDate,
             'target_date'             => $targetDate,
-            'order'                   => (int) $piggyBank->order,
+            'order'                   => (int)$piggyBank->order,
             'active'                  => true,
             'notes'                   => $notes,
-            'object_group_id'         => $objectGroupId ? (string) $objectGroupId : null,
+            'object_group_id'         => $objectGroupId ? (string)$objectGroupId : null,
             'object_group_order'      => $objectGroupOrder,
             'object_group_title'      => $objectGroupTitle,
             'links'                   => [
                 [
                     'rel' => 'self',
-                    'uri' => '/piggy_banks/' . $piggyBank->id,
+                    'uri' => '/piggy_banks/'.$piggyBank->id,
                 ],
             ],
         ];
diff --git a/app/Transformers/RecurrenceTransformer.php b/app/Transformers/RecurrenceTransformer.php
index 5e171eb140..61e6f89aa2 100644
--- a/app/Transformers/RecurrenceTransformer.php
+++ b/app/Transformers/RecurrenceTransformer.php
@@ -198,10 +198,10 @@ class RecurrenceTransformer extends AbstractTransformer
                 $destinationType = $destinationAccount->accountType->type;
                 $destinationIban = $destinationAccount->iban;
             }
-            $amount        = number_format((float) $transaction->amount, $transaction->transactionCurrency->decimal_places, '.', '');
+            $amount        = app('steam')->bcround($transaction->amount, $transaction->transactionCurrency->decimal_places);
             $foreignAmount = null;
             if (null !== $transaction->foreign_currency_id && null !== $transaction->foreign_amount) {
-                $foreignAmount = number_format((float) $transaction->foreign_amount, $foreignCurrencyDp, '.', '');
+                $foreignAmount = app('steam')->bcround($transaction->foreign_amount, $foreignCurrencyDp);
             }
             $transactionArray = [
                 'currency_id'                     => (string) $transaction->transaction_currency_id,
diff --git a/app/Transformers/TransactionGroupTransformer.php b/app/Transformers/TransactionGroupTransformer.php
index 967c077f57..1e945a135b 100644
--- a/app/Transformers/TransactionGroupTransformer.php
+++ b/app/Transformers/TransactionGroupTransformer.php
@@ -363,7 +363,7 @@ class TransactionGroupTransformer extends AbstractTransformer
         $bill            = $this->getBill($journal->bill);
 
         if (null !== $foreignAmount && null !== $foreignCurrency) {
-            $foreignAmount = number_format((float) $foreignAmount, $foreignCurrency['decimal_places'] ?? 0, '.', '');
+            $foreignAmount = app('steam')->bcround($foreignAmount, $foreignCurrency['decimal_places'] ?? 0);
         }
 
         $longitude = null;
@@ -393,7 +393,7 @@ class TransactionGroupTransformer extends AbstractTransformer
             'foreign_currency_symbol'         => $foreignCurrency['symbol'],
             'foreign_currency_decimal_places' => $foreignCurrency['decimal_places'],
 
-            'amount'         => number_format((float) $amount, $currency->decimal_places, '.', ''),
+            'amount'         => app('steam')->bcround($amount, $currency->decimal_places),
             'foreign_amount' => $foreignAmount,
 
             'description' => $journal->description,
@@ -461,7 +461,7 @@ class TransactionGroupTransformer extends AbstractTransformer
     {
         $result = $journal->transactions->first(
             static function (Transaction $transaction) {
-                return (float) $transaction->amount < 0;
+                return (float) $transaction->amount < 0; // lame but it works.
             }
         );
         if (null === $result) {
@@ -481,7 +481,7 @@ class TransactionGroupTransformer extends AbstractTransformer
     {
         $result = $journal->transactions->first(
             static function (Transaction $transaction) {
-                return (float) $transaction->amount > 0;
+                return (float) $transaction->amount > 0; // lame but it works
             }
         );
         if (null === $result) {