[FIX] point_of_sale: fixed rounding issue for pos order when discount added(maintenance: 615322).
Merge pull request #3220 from odoo-dev/7.0-opw-615322-rgo

[FIX] point_of_sale: fixed rounding issue for pos order when discount ad...
Merge remote-tracking branch 'odoo/7.0' into 7.0