A calculated field similar to the following should be able to be used:
if max(DateThru)=window_max(max(DateThru)) then 1 else 0 end
Then, place this on the filter shelf and select 1. It may be necessary to change how this calculation is computed to get the desired results (right click and select Compute Using-->desired computation).
Hope this helps!
Tracy, it is working beautifully. I do have another question. How would you create a calculation that would show the correct subtotals and grand totals? I've tried a few methods and the totals appear to sum the entire data set and not just the filtered view.