To get the total sum of min values in your grand total is a bit of a workaround (as maybe you've noticed, the grand total will use whatever the aggregation is on the measure, regardless of the table calculation that may be applied to it).
First, create a calculated field similar to the following:
IF FIRST()==0 THEN
Then, right click on TaskNo in your data box and select Duplicate. Place the TaskNo (copy) field on the Level of Detail shelf. Place the above calculation on the view. Right click on it and select Compute Using-->TaskNo (copy).
Hope this helps!
Awesome!! Thank you so much!!
Now I see the power of "Level Of Detail"
Thank you once again!