I did a web project in the gambling space ~10 years back - we were legally required to perform all calculations as integers in ten thousandths of a cent (or millionths of a dollar).
We chose to _not_ do _any_ calculations client side in Javascript...
Which regulation is that? I've worked on financial applications, but not gambling, and I've not heard of this regulation. I should probably know about it!
Australian, or possibly Tasmanian state regs. This would have been around 2011 or so (The Samsung Galaxy S2 was the "top of the range Android phone" at the time...)
We chose to _not_ do _any_ calculations client side in Javascript...