You can customize grades according to percentages for students. This video describles how you can input percentages.
Video - Final Marks for Grading
Final Marks for Grading Handout
For each grading report you can submit grades easily through Aeries. Basically what happens is that grades are imported from your Gradebook and submitted for the grading period.
Video - Loading Grades from Gradebook
Loading Grades from Gradebook Handout