By setting a levy or negative interest rate of 5 to 10 percent per year on high-denomination notes (there are various ways to do this), the government would be able to earn a large-enough stream of revenue to help offset the shortfall created by cash-using tax evaders. The effect would be a lower tax bill for all non-cheaters, both for those who generally do not use cash and those who use only small-denomination notes ($1 and €5s). In effect, the anonymity provided by $100s and €200s would now be directly paid for by the users of those $100s and €200s. Unlike an all-out ban on banknotes, financial anonymity would still be provided.

This is what inflation accomplishes, unless I am misreading something obvious? Keeping money out of financial system and hence anonymized means losing purchasing power to inflation.

Inflation is too uniform, I guess. Why not just take the $100 bill out of circulation?

Also, this seems to be falling into the classic fallacy that sovereign governments which control fiat currencies still levy taxes for revenue. Yes, it keeps things conventional and understandable to think that way, and yes, some forced circulation of currency via taxation is necessary to keep it alive, but broadly speaking, an entity like the U.S. Government does not need to collect tax revenue to function. The purpose of taxation at that level is to shape behavior and so effect policy outcomes via nudging. That still might justify a "high-denomination" bill tax, but let's not kid ourselves about "making up for lost revenue".