Totals in Sharepoint Designer

It turns out that this is pretty straightforward - but woh betide you if you try putting sum against currency - it just doesn't want to know - but if you follow these instructions http://community.bamboosolutions.com/blogs/bambooteamblog/archive/2009/04/24/how-to-total-calculated-columns-in-a-sharepoint-list.aspx should see you right.