Rounding error affecting Grade Letters

As an admin I want to be able to specify whether grade letters should be rounded down/up or not at all so that I can accurately predict the final grade letter. 

Rounding error can also be a problem. ***Letter grade can be affected by rounding if too few decimals stored. US rounding convention may be different than elsewhere (.5 vs. .9).
We need to look into the various letter scales used globally and provide additional option NOT to round letter grading.
Example: Based on the US system shown below, depending on what the rounding has been set to, a student with 89.45% may be rounded down to 89% resulting in the student not getting an A, whereas a teacher may have rounded it up to 90% resulting in the highest grade (A).
See linked issue: 65182

• A - is the highest grade you can receive on an assignment, and it's between 90% and 100%
• B - is still a pretty good grade! This is an above-average score, between 80% and 89%

Currently Moodle rounds to 5 decimal places - a user is able to specify the number of decimal places they want a number to be rounded to. Teachers find that the grades do not match their spreadsheets which causes confusion.

Global scales

• A-F: in the US, Canada, Thailand, Saudi Arabia, etc.
• 1-10: in the Netherlands, Colombia, Latvia, Israel, etc.
• 1-5: in Germany, Austria, Russia, Slovakia, Paraguay, etc.
• Percentage: in Kuwait, Belgium, Hungary, Poland, etc.
• US GPA scores: 0-4 and multiples of 4 - can be cumulative/non-cumulative, weighted/non-weighted