VAT on Base price+ Excise duty + Freight

Hi

Im using TAXINN Procedure. I have got two scenarios for VAT.

1)some vendors charge VAT on Base price+ Excise duty & then add freight.

which I have mapped.

2)In second scenario some vendors charge VAT on (Base price+ Excise duty + Freight). which I am unable to map.

how can i do it in TAXINN (condition based procedure)...

pls help..

thanks n regards

pravin