I made a small post about
Inexact rounding up or down with decimal digits.
But it is also possible to run into the same bug when rounding floating point numbers to the next number with
restricted decimal digits. A really common example is the price calculation. You have the price `1.99`

for example and the tax is maybe *19%*. The resulting price with tax would be `2.3681`

. So you will
need to round the price with two decimal digits to `2.37`

.

Calculations with floating point numbers are often producing small hidden bugs in some programming languages. For example rounding down or up with decimal digits. I want to show on some small examples in Java, JavaScript, Python and C the main problem.

I am building a small python program that is waiting for input from a bluetooth device. Depending on the input of
the device I want to update my
GUI.
My decision was TkInter,
the de-facto standard GUI for Python. But my main problem was the blocking method `mainloop`

.