This type of thing coming from programmers really bothers me. Here is a more universal rule: Never say "never."

Whether or not floating point numbers can be used depends on the context. If you are talking about an accounting system, core banking system, ERP, or similar transactional systems, then sure you probably should use integers not floats.

However, if you're working on any financial model, like something as simple as discounted cash-flow model, then floating point is the correct choice and only choice.

I've had a programmer try to convince me that I had to use integers in financial modeling software that I was developing, and he used this same folksy argument with me. It was a genuine struggle to convince him that this was not a universal law and made no sense for the application at hand.