I think you are confusing Selections with the Chart Dimensions. If the chart has dimensions Employee Name, Month and Date, then you can request subtotals ("Partial Sums" in the Presentation Tab), for those three levels.
So, maybe the missing piece is that you need to request a "Partial Sum" for the Employee dimension, and that will generate the overall total for the table.
When a Manager is selected, than the overall total for the table means also a total for the Manager.
hope it helps,