diff --git a/ChangeLog b/ChangeLog
index 1dcdfc40a1..da015996df 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -14,6 +14,14 @@
 	  or as "seventeen thousand five hundred".  Note that numbers STILL
 	  default to decimal-radix instead of asking the user to choose.
 
+	* src/business/business-core/gncEntry.[ch]:
+	* src/business/business-ledger/gncEntryLedger.c:
+	  Properly round invoice entries and totals.  Fixes #300042.
+	  Perform internal computations to LCD, but then export rounded values.
+	  Now, using the test case in Bug #300042 I get the same values
+	  in the invoice window, in the printable invoice report, and
+	  in the CoA Registers.
+
 2006-07-16  Andreas Köhler  <andi5.py@gmx.net>
 
 	* src/gnome-utils/gnc-main-window.c: Do not move windows on
diff --git a/src/business/business-core/gncEntry.c b/src/business/business-core/gncEntry.c
index a26da73d21..f7d1ba7cd5 100644
--- a/src/business/business-core/gncEntry.c
+++ b/src/business/business-core/gncEntry.c
@@ -839,13 +839,15 @@ GncOrder * gncEntryGetOrder (GncEntry *entry)
  * the amount the merchant gets; the taxes are the amount the gov't
  * gets, and the customer pays the sum or value + taxes.
  *
+ * The SCU is the denominator to convert the value.
+ *
  * The discount return value is just for entertainment -- you may way
  * to let a consumer know how much they saved.
  */
 void gncEntryComputeValue (gnc_numeric qty, gnc_numeric price,
 			   GncTaxTable *tax_table, gboolean tax_included,
 			   gnc_numeric discount, GncAmountType discount_type,
-			   GncDiscountHow discount_how,
+			   GncDiscountHow discount_how, int SCU,
 			   gnc_numeric *value, gnc_numeric *discount_value,
 			   GList **tax_value)
 {
@@ -975,11 +977,15 @@ void gncEntryComputeValue (gnc_numeric qty, gnc_numeric price,
    * need to compute taxes (based on 'pretax') if the caller wants it.
    */
 
-  if (discount_value != NULL)
+  if (discount_value != NULL) {
+    if (SCU) discount = gnc_numeric_convert(discount, SCU, GNC_RND_ROUND);
     *discount_value = discount;
+  }
 
-  if (value != NULL)
+  if (value != NULL) {
+    if (SCU) result = gnc_numeric_convert(result, SCU, GNC_RND_ROUND);
     *value = result;
+  }
 
   /* Now... Compute the list of tax values (if the caller wants it) */
 
@@ -995,12 +1001,14 @@ void gncEntryComputeValue (gnc_numeric qty, gnc_numeric price,
 
       switch (gncTaxTableEntryGetType (entry)) {
       case GNC_AMT_TYPE_VALUE:
+	if (SCU) amount = gnc_numeric_convert(amount, SCU, GNC_RND_ROUND);
 	taxes = gncAccountValueAdd (taxes, acc, amount);
 	break;
       case GNC_AMT_TYPE_PERCENT:
 	amount = gnc_numeric_div (amount, percent, GNC_DENOM_AUTO,
 				  GNC_DENOM_LCD);
 	tax = gnc_numeric_mul (pretax, amount, GNC_DENOM_AUTO, GNC_DENOM_LCD);
+	if (SCU) tax = gnc_numeric_convert(tax, SCU, GNC_RND_ROUND);
 	taxes = gncAccountValueAdd (taxes, acc, tax);
 	break;
       default:
@@ -1066,12 +1074,16 @@ gncEntryRecomputeValues (GncEntry *entry)
     entry->b_tax_values = NULL;
   }
 
+  /* Determine the commodity denominator */
+  denom = get_entry_commodity_denom (entry);
+
   /* Compute the invoice values */
   gncEntryComputeValue (entry->quantity, entry->i_price,
 			(entry->i_taxable ? entry->i_tax_table : NULL),
 			entry->i_taxincluded,
 			entry->i_discount, entry->i_disc_type,
 			entry->i_disc_how,
+			denom,
 			&(entry->i_value), &(entry->i_disc_value),
 			&(entry->i_tax_values));
 
@@ -1080,9 +1092,9 @@ gncEntryRecomputeValues (GncEntry *entry)
 			(entry->b_taxable ? entry->b_tax_table : NULL),
 			entry->b_taxincluded,
 			gnc_numeric_zero(), GNC_AMT_TYPE_VALUE, GNC_DISC_PRETAX,
+			denom,
 			&(entry->b_value), NULL, &(entry->b_tax_values));
 
-  denom = get_entry_commodity_denom (entry);
   entry->i_value_rounded = gnc_numeric_convert (entry->i_value, denom,
 						GNC_RND_ROUND);
   entry->i_disc_value_rounded = gnc_numeric_convert (entry->i_disc_value, denom,
diff --git a/src/business/business-core/gncEntry.h b/src/business/business-core/gncEntry.h
index 865322d691..349522422e 100644
--- a/src/business/business-core/gncEntry.h
+++ b/src/business/business-core/gncEntry.h
@@ -174,7 +174,9 @@ GList * gncEntryReturnTaxValues (GncEntry *entry, gboolean is_inv);
 /** Compute the Entry value, tax-value, and discount_value, based on
  * the quantity, price, discount, tax-table, and types.  The value is
  * the amount the merchant gets, the taxes are what the gov't gets,
- * and the discount is how much the customer saved.
+ * and the discount is how much the customer saved.  The SCU is the
+ * target denominator of the value and tax -- it should be the
+ * account or commodity SCU of the target.
  *
  * The tax_values list is the property of the entry and will be
  * destroyed automatically, so use it quickly.  Note that all return
@@ -187,7 +189,7 @@ void gncEntryGetValue (GncEntry *entry, gboolean is_inv, gnc_numeric *value,
 void gncEntryComputeValue (gnc_numeric qty, gnc_numeric price,
 			   GncTaxTable *tax_table, gboolean tax_included,
 			   gnc_numeric discount, GncAmountType discount_type,
-			   GncDiscountHow discount_how,
+			   GncDiscountHow discount_how, int SCU,
 			   /* return values */
 			   gnc_numeric *value, gnc_numeric *discount_value,
 			   GList **tax_values);
diff --git a/src/business/business-ledger/gncEntryLedger.c b/src/business/business-ledger/gncEntryLedger.c
index fba53c82ac..41763af9c9 100644
--- a/src/business/business-ledger/gncEntryLedger.c
+++ b/src/business/business-ledger/gncEntryLedger.c
@@ -672,16 +672,12 @@ gnc_entry_ledger_compute_value (GncEntryLedger *ledger,
 
   gncEntryComputeValue (qty, price, (taxable ? table : NULL), taxincluded,
 			discount, disc_type, disc_how,
+			100,  /* XXX -- compute a real denominator */
 			value, NULL, &taxes);
 
-  /* Now convert the values to the proper denomination */
-  if (value)
-    *value = gnc_numeric_convert (*value, 100 /* XXX */, GNC_RND_ROUND);
-
-  if (tax_value) {
+  /* return the tax value */
+  if (tax_value)
     *tax_value = gncAccountValueTotal (taxes);
-    *tax_value = gnc_numeric_convert (*tax_value, 100 /* XXX */, GNC_RND_ROUND);
-  }
 }
 
 gboolean