[IMP] removed decimal precision.

Task: https://www.odoo.com/web#id=10944&view_type=form&model=project.task&menu_id=3942&action=327
Pad : https://pad.odoo.com/p/r.t24p6lMJBRTobP85
You should not removed the round from computation, replace "prec" by the precision of the company_id.currency_id.rounding
Since company_id is not defined on this object, add the field company_id with a default value to the current society.

Same goes for the other places you removed the round() functionality