I think in my state the "Use Tax" allows the 1st $770 in purchases (for which sales tax was not collected) to be exempt. Amazon collects sales tax in my state now, however, so its a moot point as that definitely was always the vast majority of my tax-free purchases. All that being said, I don't think anyone actually puts anything down, as it is well known that is basically impossible and fruitless for the tax collectors to prove what you purchased.
Now, if you did buy some extremely expensive things tax-free, I can see wanting to avoid problems by actually reporting it. $10 million in purchased artwork or something like that could definitely cause issues I imagine! Or perhaps buying a vehicle in another state...not sure how that all works tax wise, but that could be something you need to report.
