Creating Customer Groups on the fly.

In the Contribution Cube, I'd like to group customers by the total contribution amount year to date.

Here are some example Contributions

This list would continue and would include campaigns for which I'd want to filter

Here are some example ranges

There would be more levels.  I'd also need to do this for each of 5-6 past fiscal years.  Short of a bunch of manually created formulas.  Is there a good way to get a summary like this done in Tessitura Analytics? 

Note these are not membership levels and would have to be calculated on many past years.  They are ranges that need to be calculated on the fly depending on the campaign filtering.

Anyone out there got any good ideas on how to proceed?