It depends on what your state sales tax is. Their "NRST" is really a tax "of the gross payment"
Your $10.00 item with a 7% state tax would be $13.90.
$3.90 is 23% "of the gross payment".
Another classic lewislynn lie. The NRST does not tax taxes. The state and federal sales taxes would be calculated exclusive of each other. But never let facts get in the way of lewislynn's agenda...