Suppose....
I have a summer home in New Hampshire but permanent residence in Mass. On May 1st, I purchase a car from a NH dealer and register the car in NH (NH has no sales tax). The car never enters Massachusetts during the first five months of ownership. On October 1st, I close up my NH house and come "home" and now register my car in Massachusetts. Do I have to pay sales tax on the brand-new purchase price, or is it less because the car is "used"?