Perhaps there was another way to do this within a Grid, but I couldn't find it...
We wanted to be able to track how much we spend on awards handed out throughout the year (to help with figuring out a budget). I export the following query's results to Excel & then sum the Cost column. It doesn't take into account the multipack purchases, but it's close enough for our needs.
SELECT Person.Mailing_Name AS "Name", Inventory.Description, Inventory.Cost / Inventory.Pkg_Qty AS "Cost" FROM Person, Award, Inventory where Award.Person_ID = Person.Person_ID AND Award.Item_Number = Inventory.Item_Number AND Inventory.Cost > 0 AND Award.Date_Earned between '2009-09-07' and '2009-10-14' ORDER BY person.Mailing_Name