What I’m trying to show here is that both integers and floating point are not suitable for doing ‘simple’ financial math. But we get used to this Bresenhamming in integers and do not perceive it as solving an error correction problem.
I realized something I didn't ever notice or appreciate in 20+ years: oh yeah, they can't just round off the penny in their favour every time. And the code that handles tracking when to charge someone an extra penny must be irritating to have developed and manage. All of a sudden you've got state.