Hello djem38
Have you checked the Gradebook configuration for this course period?
Isn't then because you've set in the Gradebook configuration to round grades down?
This would explain why 82.4% is rounded down to 82%, thus giving a grade of 88.
-Edit-
Even if you haven't set Rounding options, percent grades are rounded. So 82.4% will in any case be rounded to 82%, unless you configure to round scores up.