I've seen floats for money in production, not a financial system per se, but it moved amounts around external systems that often would include some financial ones. It worked surprisingly well given the amounts involved (anywhere from tens to thousands of EUR/USD), and when I asked about the off by +-0.01 errors every now I was told they were "not worth fighting by the customers".
Most customers may not care, but reports and automated processes likely will when a customer is 'in debt' thanks to small differences, and the tax authority in certain countries also care when the sum of the differences is large enough.
