product combination + state tax problem

[fawad]

Hi,
I am using prestashop version Version 1.3.1.1. I have used some product combination's there. Also i have setup state tax for Maryland. When the user is from Maryland correct prices are displayed on product page and shopping cart. But when the user is not from that state, he select a a combination product it then aslo add the state tax to combination price which should not be.
For example:
I have added a product with name xyz
The default price of the product is 50$
i added two combination's with it.
Large with price impact on 100$ increase
Medium with price impact on 50$ increase
And the state tax is 5%.
Ok now for Maryland customers the prices should be:

Default 52.5$
Large product price should be 157.5$
Medium product price should be 105$
Up to this point every thing working fine.
But when the customer who do not belong to Maryland state log in
Then it display the prices wrongly
e.g
For default it display correct 50$
But for long product it display 155$ which should be 150$.
For medium product it display 102.5 which should be 100$.

Please any body have any solution for i should be grateful
Thanks