Tax
Federal law requires businesses to charge tax in all states they do business in esp. if they have a physical presence in that state.
Edit-Sorry, looks like others have already addressed this question.
Apparently Amazon has a choice in the matter.And this goes for iPods too or Mac computers. You can buy from Apple and get charged sales tax or buy from Amazon and avoid sales tax. Why is that? Is it really because Apple has no choice? I don't think so. When I used Rhapsody, they charged 89 cents for songs if you were a subscriber. No sales tax. And you could re-download your songs if you wanted to.
Federal law requires businesses to charge tax in all states they do business in esp. if they have a physical presence in that state.
Edit-Sorry, looks like others have already addressed this question.