Bug 22791: Unify calculation between aqui-home and ordered.pl

Bug 22791: Unify calculation between aqui-home and ordered.pl

To test:
1 - Enable order price rounding
2 - Order an example with 8 * 16,99 and 42% discount, 19.45% tax.
3 - Check ordered page - 94.17 is total
4 - Check aqui-home - 94.16 is total
5 - Apply patch
6 - Verify numbers now match

Signed-off-by: Maryse Simard <maryse.simard@inlibro.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>