Pro-Sites doesn't allow charging taxes

Hi.

PayPal comes with a tax calculator. Easy and powerful. But… only PayPal Payments Standard! Which was supported by Supporter but not by Pro-Sites anymore. In other words: Pro-Sites doesn’t allow charging taxes! And we’d like to avoid any tax related trouble with any government, wouldn’t we?

I called PayPal support and went through their documentation, and the only way I’ve found so far to add taxes is to use the callback feature, which I guess relies on shipping information and requires SSL.

Am I missing something? Has anyone else experienced the same issue? Is there an easy workaround? Should a module or something like this be developed to handle PayPal’s callback? Should I develop my own? How?

Thanks.