@Rob, what you mean, I think, is that RapidCart Pro can handle such transactions. The vendor must still register for VAT (if he/she is not already registered) and account to the tax authorities. This is a very unwelcome additional burden for many of us.
I’m very impressed with what RapidCart Pro offers but my main business is printed books which are VAT zero-rated in the UK and so I don’t need to be registered for VAT unless I want to sell electronic products directly from my website. In any case the UK VAT threshold is £82,000 p.a., way above my turnover. For me and, I suspect, many others, the extra paperwork is something we could do without.
@ashleykaryl yes FastSpring do seem to handle all that – at a rather hefty price.