Discount after exise and before VAT

Hi,

We have a requirement like this

Basic Price Rs.100/-

Excise 10% 10/-

Discount Rs 20/-

Vat 4% Rs.3.60/- (100+10-20=90*4)

I am not able to resolve this requirement in 5.0 and 6.0

I have resolved in 4,7 by using sub total 6 in Discount condition in MM pricing

but it is not happening in ECC 5 and 6 system is calculating Vat on Rs.110/-

Thanks

Prasad