Round base amount of commission using price digits

Closes #12018

modules/commission/commission.py

@@ -345,7 +345,7 @@ class Commission(ModelSQL, ModelView):
         states=_readonly_states,
         help="The product that is used on the invoice line.")
     base_amount = Monetary(
-        "Base Amount", currency='currency', digits='currency',
+        "Base Amount", currency='currency', digits=price_digits,
         states=_readonly_states)
     amount = Monetary(
         "Amount", currency='currency', required=True, digits=price_digits,

modules/commission/invoice.py

@@ -179,6 +179,7 @@ class InvoiceLine(metaclass=PoolMeta):
             with Transaction().set_context(date=self.invoice.currency_date):
                 base_amount = Currency.compute(self.invoice.currency,
                     self.amount, agent.currency, round=False)
+            base_amount = round_price(base_amount)
             amount = self._get_commission_amount(base_amount, plan)
             if amount:
                 amount = round_price(amount)

modules/commission/tests/scenario_commission.rst

@@ -155,7 +155,7 @@ Post invoice::
     >>> len(line.commissions)
     2
     >>> [c.base_amount for c in line.commissions]
-    [Decimal('100.00'), Decimal('100.00')]
+    [Decimal('100.0000'), Decimal('100.0000')]
     >>> [c.amount for c in line.commissions]
     [Decimal('10.0000'), Decimal('10.0000')]
     >>> [c.invoice_state for c in line.commissions]