Problem with rounding!!!

I made new invoice with this data:

Item_1     Qnt-16  Price-11,79  Disc%-4,3 PriceDisc - 11,28   Total - 180,53

This is error, because 16 x 11,28 is 180,48, not 180,53

Where can I change rounding price after disc, because 11,79-4,3% - 11,28303 not 11,28.

Thanks,

Robert