precision differs from total price.
Price precision using 'getPricePrecision' unit price extension from r32328 is not
supported for now, this commit is just to restore precision from
currency.


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@39065 20353a03-c40f-0410-a6d1-a30d3c3de9de