Rounding regression from the bugfix #344187 (trunk)

Hi!
Trunk version.
The fix for bug #344187 introduced a regression with rounding.
With a supplier invoice in a foreign currency.
In account_move.validate():
            for line in move.line_id:
                amount += line.debit - line.credit
This amount calculation before the fix was 0.0, now with the fix I get 0.019999999785795808

The supplier invoice:
6000x2.91
3000x3.58
1000x1.04
2000x1.12
1000x1.2

The currency conversion rate: 0.0146665415