Reduction amount of without Tax

[eGzyl.pl]

hello i want add Reduction amount to price without tax, now is add to price with tax somebody know what i must change to have what i need ??

THX FOR HELP

for example how is now

price 10
price with tax 12
Reduction amount: 2
amunt after reduction : 10

but i need: 8+tax

[eGzyl.pl]

somebody know ???????????

[tomerg3]

My tax modification does that, in addition to displaying the tax on a separate line.

You can get it from my store, and use only the parts you need.

[eGzyl.pl]

but where i find it??

[tomerg3]

http://www.presto-changeo.com/15-taxman.html

[goodbreeze]

I am looking for something that changes the fact that when a reduction is made to pre-tax retail price, the tax is NOT applied to the FINAL RETAIL price. It is instead taken on the pre-tax price. Prestashop is charging tax on the wrong amount. Any ideas?

I described it here: http://www.prestashop.com/forums/viewthread/87638/configuring___using_prestashop/tax_on_is_being_charged_on_pretax_retail_price_instead_of_final_retail_price