This may not answer your question, however I have two stories.
Because some States will charge you the State Sales Tax for that State, you have to be careful where you buy.
1. I purchased a car in New York State and drove it to Florida.
All it takes in NYS is for you, or the dealer, to go to the DMV, show proof in insurance for that car and get an "In-Transit" Permit. (Paper Plate). You do not pay the NYS Sales Tax and you must get the car out of the State with 30 days. Had no problems driving it to Florida where I paid the State Sales Tax when I registered the car. (Some dealers don't even know about this, and you have to "inform" them of the law).
2. I purchased a car in Littleton Colorado (Denver area). Had a slight problem getting a paper plate, because the DMV office we went to, wants an address in the same county where the DMV office was located. They don't want to know nothing about me being from out of State. They want an address from that county. Well, the guy I bought the car from, lives in a different county, even though it was all Denver. Lucky for me, he has a daughter who lives in that same county, so we just used his daughters address and my name. Showed proof of insurance and got the temporary plate. The paper plate is the type that sticks to the rear window, not the license plate frame. Had no problems once I got that paper plate. Drove down to Roswell NM for a few days, then back to Florida.
As noted in (1) above, some States (like Florida) insist you pay that States Sales Tax, then they tell you that when you get to register the car in your home State, all you have to do is show that you paid the tax. All I can say is to CHECK WITH YOUR HOME STATE DMV FIRST. I've heard horror stories where the home State would not recognize the tax paid in the selling State, and the buyer had to pay the tax a second time in the home state.
Be careful my friend. Very careful.