Like I said, it differs state by state. For instance in California, there is no tax on bullion unless the purchase is $1,000 or greater.
Oregon has no sales tax at all! Always freaks me out when I buy something there and they actually charge what the listed price is. Kinda weird feeling.
Like I said, I have no idea what the state to state differences are. Just that the northeastern states seem to have this common “sales and use” tax that covers many things that are bought, or brought into the state for personal use. I would think that many states had a similar “capital gains” tax that followed the federal example, make some money - you gotta pay us a percentage.