Its a really silly question but I must do it 
:
It’s a problem if you don’t round the numbers of your calculation?
To be clear: it’s more efficient to have numbers like 2.35 or 2.34987605049384 when GD make his calculations? Or it doesn’t change anything at all?
It is depends on how you want to use this number and how accurate you want it to be.
For example if you want to change the position of something exactly by 2 pixels then you need to round it, otherwise it is not that important as long you get the result you expect.