Numismatic Overhaul The Three Coins

There are three denominations, and they convert at a flat rate:

Any amount of money can be written as at most one number of each, the same way real change works — 12,345 bronze is 1 gold, 23 silver and 45 bronze.

The coin icon changes as the stack grows, so you can read roughly how much is in a slot at a glance: a lone coin, a small handful, a heap, and a full pile all draw differently. Coins stack higher than ordinary items, and dropping one stack onto another of a smaller denomination merges them into the larger coin automatically.