Snap Rotation Problem

Hello, I have problem on rotation snap, i searched for the problem but i didnt find any clear answer.
When i rotate a model with the snap tool (ctrl + rotate axis)
The rotation are going wrong




This is a unity original 3d cude

So each time i rotate snap to 90 the rotation come working 90.00001 and -89.99999
I only get this on rotation axes (x, y, z), transform snap are just working good
And it make my scene snap come wrong after some object snap distance as floor ...
I have Unity 2018.4.0.f1 but i think it does it in most to not say all of the version that i own.
Do you have an idea how to fix this ?


Thanks
Regards