A lot of times, though, currency is not fixed. Stock share prices can be in fractions of a cent; per-unit cost numbers can easily have fractional cents too, just for a couple of quick examples. Sure, if you're just looking at your bank account, or itemizing actual transactions, they're going to be in whole cents only, but lots of financial calculations need more precision than this.
Having different numeric types for currency amounts (integer) and for costs or prices (floating point, whether decimal or binary) is not undesirable. Heck, it's very likely a bonus.
That sounds like a recipe for disaster. If you have fractional unit prices, and multiply by the number of units, floats can still give you errors. No, fixed decimal types definitely have their uses.
