Would you please share little bit of sample data (Columns, sample records)?
If possible, can you share an example workbook? This helps out a lot when trying to come up with a workable solution.
From the sounds of your req, we most likely can LoD expressions instead of Table Calcs (Assuming you are on V9.0 or up) . This is what will allow you to define the level of aggregation, without having to have lower level dimension in viz/worksheet.
If you are not familiar with LoDs, please refer to these articles
Here is also a link (to several other links) on the topic of LoDs, how they work, and how to implement them.
If you run into any problems, or get stuck, please let us know.