title: Access Report - Can't add a sum for a calculated currency column
body: <p>I've generated a simple access report that is used for purchasing.</p>
  
  <p>Basically, there are two tables, one for purchase orders, and one for the items on the purchase orders.</p>
  
  <p>For the items on an order, I store the item details, quantity ordered, quantity delivered, and price per unit. (plus a few other fields which aren't relevant in the context of this question).</p>
  
  <p>I'm generating a report to list all outstanding items still on order, and the report has a calculated field showing the outstanding quantity * cost per item. This works perfectly fine.</p>
  
  <p>What I'm struggling with, is showing a sum of this calculated field (i.e. a total cost of all outstanding items), but when I try to add a total to the column, it only gives me the option of adding an item count for the column. The column is a 'Currency' field.</p>
  
  <p>What might I be doing wrong, or am I expecting too much from access?</p>