Grades and Grad/Med School

Can someone please explain to me the idea of only seeing our grade ranges (12 for 90-100, 11 for 89-85, etc.) and how grad schools and med schools use this to make grade average calculations. Do grad/med schools get access to the actual percent and use these numbers to make an average and we don't? Is there a way we can see it? Or when calculating grade averages, are they also limited in the same way we are and use the 12s or 11s to make their average calculations.

Meaning wheter I got say a 95 in a course for instance, would that be treated the same as if I got a 90/100 or is that percent actually used? Would this vary for each grad school or med school?

I'm sure this question has been asked a lot but I just need an explanation for how it truly works. Thank you.