I live in Georgia near the Ga.- Al. state line. In the past I bought a Ktm 50 from a Alabama dealer and didnt have to pay any sales tax. This past summer I bought two quads from a different Alabama dealer and was told I had a choice to pay Alabamas 2.5% sales tax or pay Georgia's 7% tax. I was told if I didn' pay any sales tax the purchase would have to be reported to my home state and that at some point Georgia would come after me to collect the tax. I dont know if the dealer was blowing smoke up my rear end or not because in Georgia we dont have to register our Atv's. You can probably guess which tax I chose to pay. On the Honda 90 it was only $50 and the 250Ex it was around $100 . The dealer worked us a pretty good deal compared to the dealers in Georgia. No freight, no set up fees and discounted both Atv's below list price. The dealers in the Atlanta metro area think everybody around here has a high producing money tree growing in their backyard and wouldnt even consider any type of negotitions. I wish I could give the dealer in Oxford,Alabama a plug. The one that sells Honda's,Kawasaki's and Susuki's, but I dont know if that would be prudent.
So to answer your question I think it vary's from state to state and sometimes dealer to dealer.