[xp84]

This may be the most practical go-forward plan. The Euro's .20 coins are also attractive too. But you're correct that quarters, as the smallest common currency that you can plausibly buy something with just a couple of them, are just everywhere, from laundry to car washes, so the pain in retiring them would be widely felt.

What I've learned from the penny retirement is that people are deeply distrustful of simple high school level statistics! Millions of people have angrily seethed that somehow stores are or will be using the penny retirement to rob them, despite knowing that most transactions have an unknowable amount of different items, and sales tax, so attempting to manipulate prices to gain a statistical advantage out of rounding would be incredibly difficult and would yield a pitiful return. Let alone how the cash transaction share is declining every year.

[estimator7292]

We need to keep the physical dimensions and material properties of the quarter, but why not change the face value? Demote them to 20 cents, or even better, make them 50 cents because the real half dollar coin is obnoxiously huge and impractical.

What of the economic impact of doubling the value of all quarters? Eh, it'll probably be fine. We'll just write it off as an AI datacenter loan somehow

[xp84]

I have long believed that changing coin value upward would be the #1 way to get 100% of citizens on board with currency reform. Or at least buy them from citizens at above face value.

Unfortunately, I think that vending machines specifically would frustrate this scheme though, because you can bet that most operators of them would, rather than reprogramming the machines which would be expensive (especially given how many old machines must be out there without any manufacturer support available), just leave everything the same physically and double all their prices.