You pay sales tax to the state in which you reside.
Note "reside" is the legal definition of residence.
If you reside in New Hampshire, you do not pay sales tax on a vehicle, even if you buy it in Massachusetts or New York or anywhere else.
If you reside in a state WITH sales tax (Massachusetts) and buy from a state with NO sales tax (New Hampshire), you STILL pay sales tax at the time of registration.
If Jerry "moved" to Oregon, he could establish residency there and not pay sales tax on a car purchase. However, if he was doing this to get around the tax laws, he would most likely be caught for 2 reasons:
1) Most states have laws that you must register a vehicle within a certain period of time. If he kept driving on his Oregon plates, eventually it would raise suspicion and he'd get pulled over and ticketed, and if it came up on the states radar screen, you better believe they would be looking for their tax money.
2) Most states have mechanisms in place whereby they check for this sort of thing. If I file a MA tax return on a MA address, but my car is registered in NH, it's gonna raise a red flag. It would be a real PITA to have a second 'residence' just for tax purposes - because all your mail woudl go there, etc, etc.
My question would be - if one moved from Oregon to California, they do not pay sales tax - only registration fees. So, how long does one need to "live" in Oregon before "moving" to California to avoid raising a red flag? Or does nobody know?