I don't see how it could be possible though, since the very institution that does audits (the IRS) would be shut down.
Under HR25, states tax authorities would be administering the NRST in parallel with there own sales tax systems. One of the tools they use to promote compliance is to audit retail businesses for tax compliance when they have reason to suspect a business is defrauding or evading the retail sales tax system.
The effect on retail business would be no greater for having to account for there gross sales receipts under a state's current sales tax and one with the NRST along with it.
Any tax system will have the means to enforce its provisions. The key to a retail sales tax is that only those business that chose to engage in sales of new products for final consumption (as opposed to selling to other businesses or the sale used products on which the NRST has already been paid) are subject to NRST enforcement to assure that taxes are collected from the customer and once collected are indeed remitted to the state tax authority.
Interesting, so audits would still continue. I stand corrected Your Nightmare.
However, I think the point ancient_geezer makes is a good one: Retail businesses are already affected by state sales tax audits, thus, the impact on them would probably be minimal.
And of course, as we all agree, individual audits would be eliminated, which is a good thing too.