Google Checkout VAT calculation

Hi...
I have installed google checkout on my Zen Cart.
I am trying to add VAT 17.5% when person buy from GCO. but on starting its taking zero vat amount. then from some where on forum i come to know that to add VAT make tax true in responsehandler.php file.
by doing this now i get £7.54 fix VAT on every purchase. my seller account is from UK and buyer is from UK or US.
I have updated tax-class and tax-rates.
any one have idea how to add VAT exactly to GCO ?

I have used Google checkout sandbox..

Hi Moni,

I think you can set the tax rate in the Google Checkout settings.

Am just having a play with it myself and have just set the tax rate at UK 17.5%.

hmm, apparently sandbox does not calculate the vat properly, but the live account does. according to...

http://www.daniweb.com/blogs/entry1659.html