[FIX] point_of_sale: properly round taxes with round_globally

When tax_calculation_rounding_method is configured to round_globally the
compute_all method of account.tax will not round the taxes based on the
currency. The result of the compute_all function is used when creating
the tax parts of a pos.order account.move.

Taxes are aggregated per session, so 2 orders with orderlines in them
with the same tax will turn into 1 single tax account.move.line. To
correctly handle round_globally, we round all tax values we have after
processing each order.

Fixes #14672
Fixes #14673

addons/point_of_sale/point_of_sale.py

@@ -1295,6 +1295,7 @@ class pos_order(osv.osv):
 
         grouped_data = {}
         have_to_group_by = session and session.config_id.group_by or False
+        rounding_method = session and session.config_id.company_id.tax_calculation_rounding_method
 
         for order in self.browse(cr, uid, ids, context=context):
             if order.account_move:
@@ -1420,6 +1421,14 @@ class pos_order(osv.osv):
                         'partner_id': order.partner_id and self.pool.get("res.partner")._find_accounting_partner(order.partner_id).id or False
                     })
 
+            # round tax lines per order
+            if rounding_method == 'round_globally':
+                for group_key, group_value in grouped_data.iteritems():
+                    if group_key[0] == 'tax':
+                        for line in group_value:
+                            line['credit'] = cur.round(line['credit'])
+                            line['debit'] = cur.round(line['debit'])
+
             # counterpart
             insert_data('counter_part', {
                 'name': _("Trade Receivables"), #order.name,