Currently there are many settings in Moodle that will allow any grade to be rounded from 0 decimal places up to 5. The rounding of grades is purely cosmetic and has no impact on the grade stored in Moodle.
One drawback of how rounded grades are currently shown is that if a grade is rounded up, a student may be confused, as the grade looks like a pass but it is actually not.
To avoid this sort of situation, we consider that rounding down, or flooring, the display grade would be the optimum solution. The real grade is not affected in any way. The student's position of pass or fail, or A or B, are not changed. It just give a clearer view to the student that the cut off was, or was not reached.
For further details please refer to MDL-21746.