diff --git a/purchase.py b/purchase.py
index 83d05f8ca4..470793bea8 100644
--- a/purchase.py
+++ b/purchase.py
@@ -1,7 +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 trytond import backend
 from trytond.i18n import gettext
 from trytond.model import ModelSQL, ValueMixin, fields
@@ -11,6 +9,7 @@ from trytond.pool import Pool, PoolMeta
 from trytond.transaction import Transaction
 from trytond.tools.multivalue import migrate_property
 
+from trytond.modules.product import round_price
 from trytond.modules.purchase.purchase import (
     get_shipments_returns, search_shipments_returns)
 
@@ -181,11 +180,9 @@ class Line(metaclass=PoolMeta):
         Currency = pool.get('currency.currency')
         move = super().get_move(move_type)
         if move and self.purchase.customer:
-            digits = move.__class__.cost_price.digits
             cost_price = Currency.compute(
                 move.currency, move.unit_price, move.company.currency)
-            move.cost_price = cost_price.quantize(
-                Decimal(str(10.0 ** -digits[1])))
+            move.cost_price = round_price(cost_price)
         return move
 
 
diff --git a/stock.py b/stock.py
index 53dae3b76a..891753a890 100644
--- a/stock.py
+++ b/stock.py
@@ -17,6 +17,7 @@ from trytond.transaction import Transaction
 from trytond.tools import grouped_slice, cursor_dict
 
 from trytond.modules.sale.stock import process_sale
+from trytond.modules.product import round_price
 from trytond.modules.purchase.stock import process_purchase
 
 
@@ -402,7 +403,6 @@ class ShipmentDrop(Workflow, ModelSQL, ModelView):
         Move = pool.get('stock.move')
 
         to_save = []
-        cost_exp = Decimal(str(10.0 ** -Move.cost_price.digits[1]))
         for shipment in shipments:
             product_qty = defaultdict(int)
             product_cost = defaultdict(int)
@@ -454,7 +454,7 @@ class ShipmentDrop(Workflow, ModelSQL, ModelView):
             for product, cost in product_cost.items():
                 qty = Decimal(str(s_product_qty[product]))
                 if qty:
-                    product_cost[product] = (cost / qty).quantize(cost_exp)
+                    product_cost[product] = round_price(cost / qty)
             for c_move in list(shipment.customer_moves) + to_save:
                 if c_move.id is not None and c_move.state == 'cancel':
                     continue
diff --git a/tryton.cfg b/tryton.cfg
index 84b3303374..8c9b11afe0 100644
--- a/tryton.cfg
+++ b/tryton.cfg
@@ -3,6 +3,7 @@ version=5.5.0
 depends:
     company
     ir
+    product
     purchase
     purchase_request
     sale