How is it possible to get a 10.03 GPA

From what I have heard, most high schools grade regular classes on a 4.0 scale, Honors on a 4.5 scale, and AP / IB on a 5.0 scale. This means that the highest possible GPA if you took all AP classes would be a 5.0. Even if you have above a 100 average somehow, a 5.0 is the highest that can be obtained. I have heard that some high schools, to make their students look smarter, add 1.0 to each of the values above so that the largest possible is a 6.0.

Isn’t there no possible way to earn a 10.03 GPA so long as the school does not just change the scale to be a 10.03 or above? Does it discredit the school of they do this or does it actually benefit the applicants?

http://www.americanbazaaronline.com/2014/06/04/indian-american-student-florida-attains-incredible-10-03-gpa/

Most colleges recalculate GPA on their own terms, anyways, so it doesn’t matter. This student’s school’s GPA scale was probably just wack.