Learn@UW - Potential for Final Grade Rounding Errors in Weighted Gradebook
If the gradebook in your course is using the weighted system, the calculated and adjusted final grades may differ slightly from the correct values.
It is possible for a student to receive a final grade a small fraction of a percent off the true final grade. If a letter grade scheme is used, some students could possibly be awarded the wrong final grade. For example, a student's true final grade may be an 80% which is the cutoff for a 'B' in the course, and the calculated or adjusted final grade may be 79.99983%, resulting in a 'BC' or 'C'.
Any inaccurate grades are in categories where the option "Distribute weights evenly across all items in the category" has been set. For this reason, this option should be used with caution. If you use this option, check for final grades that are at or near the boundaries of grade scheme ranges.
An example of how this may occur is where you have 12 grade items in a category you want equally weighted. The correct weights of 8 1/3% for each item cannot be exactly stored. This causes slight rounding errors. Rounding errors do not occur if you supply explicit weights and turn the above option off.