The problem with your meter analogy is that the length that a meter is measuring isn't slowly shrinking. If, in 50 years, instead of my room being 5 meters across it was instead 50,000 meters across, then yeah, I'd probably recommend we start measuring rooms in kilometers. And whereas I would care if you told me my 5mx5m room was actually 4.5mx4.5m, I probably don't care that my 49999.5mx49999.5m room is missing that exact same half meter.
And think of it this way. If Walmart (or any other store) were to, instead of "stealing your extra pennies by rounding up to the nearest 5¢," simply raise the price of all your groceries by 2ish¢, would that change your buying habits? Would you suddenly refuse to buy your groceries or go drive to another store because they raised the cost by 2¢? Probably not. So, if that extra 2¢ was super meaningful to the bottom line, they could already steal it from you. They don't need the pretense of rounding.
This has been proposed for a long time, and it's been luck of the draw which administration chose to do it. You're letting your hatred of Trump make you jump through irrational hoops to try and justify why this has to be a bad thing, because they idea that it could possibly be good, even by purest luck, is a threat to your identity as a person.
Or maybe not. Maybe I'm just armchair phycologist-ing. But your stance isn't a reasonable one. If in the future an apple costs $5000 and we're still printing the penny, there's no logical framework for keeping the penny. It would take 500,000 pennies to buy an apple. You'd have to bring in a pallet of pennies to buy it. If you think we should keep printing the penny at that point, then I don't think we'll ever see eye to eye.
But if you do agree that once apples are $5000 a piece we can stop printing the penny because it has no use, then we're just arguing about where/when the line is to get rid of the penny, not that the line exists at all. And if that line exists, I think it's fairly obvious on its face that we're overdue.