Round float according to uncertainty

[Larz60+]

you can use fixed point arithmetic, where you have full control over rounding
python.org has a section on this method here: https://docs.python.org/3/library/decimal.html

This, by the way, is the same method that we (Spectrochemical engineering Lab, Instrumentation Laboratories 1980's) used to do all of the math for a scanning plasma monochromator. Never used floating point. Programming language was forth.