Change scorecard scale to 5 point scale instead of 100 point scale

the 100 point scale is tough for us to truly understand sometimes. For example, whats the main difference between a score of 65 vs 75? We would really like to have a simple 5 point scale to make things simpler to understand. Is there any way to make the scorecard a 5 point scale instead of 100 points? And if so, is there a mass edit option to change the numbers to the new scale?
If you want an indexed scoring, you might look at using what is called the "A-F" grading scheme.  You can change the labels to be whatever you want but think about it as a scoring with fixed values (and colors).  One caution is when changing the scheme you will change the underlying numbers as this scheme will use the average and not the exact value.  An "A" has one value, a "B" has one value - not a range of values.  You would need to update the Scorecard history and you could do this via SFDC Data Loader.