> Most likely they will tune for increased volume as people spend more to avoid losing a couple of cents.

Why would they ever tune for that? “Uh oh, turns out customers are intentionally spending more money!”

I don’t understand how this same train of thought comes up every time eliminating pennies is raised. This whole train of thought collapses if you consider the scope we’re talking about (literally a couple of cents max per transaction) and how stores actually behave today. Stores are happy to drop a couple of pennies to make prices look better. But in this hypothetical world stores are going to calculate the optimal prices to round in a way that rips off customers for a couple of cents. This makes no sense. They give up a penny on nearly every item today for the sake of “pretty” prices.

Edit: Oh, I see you’re arguing that they would tune to encourage spending up to “save” the couple of cents, rather than retuning in response to the hypothetical increased spending. No doubt they would like to do this. I doubt they actually would because this is not trivial and it would require ruining the pretty prices.