The issue isn’t whether rounding sometimes goes down; it’s that rounding injects randomness into something that is supposed to be exact. Cash is the one form of money the state prints, controls, and protects with criminal law. You can’t counterfeit it. You can’t alter it. It is supposed to be perfectly fungible. But once you force rounding, a five-dollar bill can settle to $4.95 or $5.00 depending on the totals, which means the same bill now has different settlement outcomes based on a mathematically biased process. That’s not fungibility. That’s drift.
And the drift isn’t neutral. Retail prices overwhelmingly end in .99, .98, and .97. Those endings push totals just below nickel boundaries, so rounding skews up more than down. Sales tax doesn’t cancel this it adds another fractional layer, that you guessed it.. must be rounded again, stacking abstraction on top of abstraction. Even if one transaction rounds in your favor, the system as a whole pushes in the opposite direction. These are small losses per purchase, but they are systematic, not imagined. Over millions of transactions, they become real transfers of value.
This is why it isn’t paranoia: the state demands exact cents from you when you pay taxes, yet forces probabilistic cents on you when you pay with cash. Precision for them, randomness for you. Rounding breaks fungibility, undermines cash’s core function, and creates a quiet form of extraction, a constant one. This is modern coin clipping, just with decimals instead of silver.
