Set analysis is one way of solving this, but given your requirement to display the information for the manager without them having to make a selection, I'd recommend taking a look at SECTION ACCESS. This will allow you to tie each manager to the departments that they have visibility into and what totals they therefore can see. When a manager opens the document, they will be prompted for a credential and that will limit the data that they see within the document (by department).
The script section of the QV Reference manual has a good description of how to setup section access in your document. Consider who needs to see what and if anyone needs the super view as you design this.