Greg,
Is it something else I should be doing with rules, because the Xpath seems to be right. When I put it in and click verify it's not coming up with any errors. When I click the drop down department box, it doesn't change amounts. Could you give me more insight please. If anyone else can help, I would appreciate it.
sum(xdXDocument:GetDOM("TOSSReceive")/dfs:myFields/dfs:dataFields/d:TOSS[@employeeDepartment = ../../dfs:dataFields/d:TOSS/@employeeDepartment]/@monthlyExpenses)