Add round_price

We add a common method to round prices that are stored using the price digits.
It is useless to use the digits from the field because it can not be changed in
any other way than by configuration.

issue9146
review299521002

stock.py

@@ -1,6 +1,5 @@
 # This file is part of Tryton.  The COPYRIGHT file at the top level of
 # this repository contains the full copyright notices and license terms.
-from decimal import Decimal
 from functools import wraps
 
 from trytond.model import ModelView, Workflow, fields
@@ -8,6 +7,8 @@ from trytond.transaction import Transaction
 from trytond.pool import PoolMeta, Pool
 from trytond.pyson import Eval
 
+from trytond.modules.product import round_price
+
 
 class Location(metaclass=PoolMeta):
     __name__ = 'stock.location'
@@ -211,8 +212,7 @@ class Move(metaclass=PoolMeta):
                 taxes=[t.id for t in line.taxes]):
             line.unit_price = Product.get_purchase_price(
                 [line.product], line.quantity)[line.product.id]
-            line.unit_price = line.unit_price.quantize(
-                Decimal(1) / 10 ** line.__class__.unit_price.digits[1])
+            line.unit_price = round_price(line.unit_price)
         return line
 
     def _get_customer_invoice_line_consignment(self):
@@ -256,8 +256,7 @@ class Move(metaclass=PoolMeta):
                 taxes=[t.id for t in line.taxes]):
             line.unit_price = Product.get_sale_price(
                 [line.product], line.quantity)[line.product.id]
-            line.unit_price = line.unit_price.quantize(
-                Decimal(1) / 10 ** line.__class__.unit_price.digits[1])
+            line.unit_price = round_price(line.unit_price)
         return line
 
     @classmethod

tryton.cfg

@@ -5,6 +5,7 @@ depends:
     account_invoice_line_standalone
     account_invoice_stock
     ir
+    product
     purchase
     sale
     stock