Price not getting displayed correctly; with attributes

[devyani]

Hi,
I have used radio buttons to price a product, based on its sizes.
So in the pricing screen I have kept the price as 0. This is an exempted product, hence I have created a new tax class called "no vat" & mentioned the rate as 0%.
attaching the screen shot for the same:


Next in the attribute section I have done the following setting :


On this category I have put a discount of 10% thru salemaker.

But, if you see the website - the amount next to radio button has not taken the discount, whereas the amount next to the price is showing the discount.

Another funny thing is that despite mentioning "no vat", a vat of 5.5% is added on each of these products in the attribute window. I have highlighted that in the image above.
I have a vat category of 5.5%, but clearly I have not defined it here.
I have no clue what to change where. Please help !