I'll use the jQuery plugin for presenting the user with a nice interface

The request is to display 5 stars, up to a total score of 10 (2 points per star).
By now I thought about using 7/10 as a format for that value, but what if at some point in the future I'll receive a request like

We would like to give users more choice, let's increase the total score to 20 (so that each star contributes with a maximum of 4 points)

I'll end up with a table with mixed values for the "star rating" column: some will be like 7/10 while others will be like 14/20.

Is it ok for you to have this difference in the database and deal with it in the logic layer to have it consistent? Or is preferred another way so that querying the table will not result in inconsistent results outside the application?
Maybe floating point values could help me, is it better to store that value as a number less than or equal to one? So in each of the two examples the resulting value stored in the database would be 0,7, as a number, not a varchar, which can be queried also outside the application.

What do you think?