Aggregate sum of report column based on a condition

Aggregate sum of report column based on a condition

I have a "Orders" report with both pending & completed orders and a column indicating whether a particular order is still pending. It'd be useful to somehow display the sum total of the "Order Value" for all orders with status "Pending"

How can I do this & where is a natural place to display it? Is it a separate report (a dashboard?) or can it be put into the summary of this same report? 

Any tips how I can do aggregations of this sort?