Rounding problems with 3, 6, 7 and 9 star widgets

Here's an example:
When using a 7 star voting widget, a user gives a piece of content a 1 star rating. Each star equals 100 / 7 = 14.285714285714286 percent. This gets rounded up and stored as 15 through VotingAPI. When the average number of stars are calculated this comes to 15 / (100 / 7) = 1.05, which is rounded up to 1.1. So 1 vote of 1 star gives you an average of 1.1 stars.

An easy fix is to remove 3, 6, 7 and 9 stars as options. I guess another way would be to add a custom tallying function that adjusts the maximum according to the set number of stars. That would make it difficult to make a change to the number of stars later though.