I just always paid the "safe-haven" tax when I lived in Massachusetts. I figured I bought enough online that it was cheaper than actually adding up all the things I bought and then paying use tax on that. It was certainly easier....which they count on (particularly since they still have no way of confirming any of it).
Every state that has a sales tax has a corresponding use tax. The use tax was part of the original sales tax law. It's there to close what would be huge loopholes for cars and other big ticket items.
You mean you don't want to be a good citizen and give the state of Tennessee your money to administer in what would most certainly be an efficient, cost-effective manner?