The whole avoid floats thing just isn't true. I have 20years experience in fintech and most of it used doubles. Excel uses doubles. Your frontend will use doubles. All your db supports doubles. Your stdlib knows how to parse doubles. Json uses doubles (not in theory but in practice). Many ERP system uses doubles

The thing for working with currency with doubles is that you have to keep in mind that it can hold 15 digits of precision in total. As long as your numbers don't use more digits than that, like 123456789.01 or 123.456789, you can have perfect decimal precision in your financial math. You just have to always round the result to within 15 digits of precision after each computation, and before each comparison. That's what excel does.

The biggest advantage of doubles is that 1) they're widely supported and 2) you can mix different precision in your system, which will appear if you do international finance or advanced financial products. Some accounting require precision up to the thousandth, some need to be rounded to multiples of 0.25. So at the end of the day you'll never use basic math but some specialised accounting math library and that library can perfectly use float as a backend.