Create a graded group assignment with one submission per group that is linked to gradebook.
As a student in that group, submit to that assignment.
As instructor, select to grade that submission
Select option on grade screen for grade override
Enter unique scores for a couple students in the site.
Press save and release to student.
View the gradebook in the site as student/instructor
All will look correct.
As instructor, go back to Assignment screen. On main score screen, select "Release Grades" link.
The scores will display as multiplied by 100(see screenshot)