Cool research, thanks for being one of the few to bring substantial arguments to this discussion.

For your first point, I would like to add the next sentence for context: "That means that a typical grocery store would receive an additional estimated $157 in revenue just from rounding." I feel like this is negligible.

Also, for the nickel, the seigniorage ratio is 2.something, isn't that lower than the penny? I think there's a decent chance that removing the penny would still be a net benefit for the mint.