httpwebwitch - 3:24 pm on Jan 30, 2012 (gmt 0)
>> so I can use that value in other pages
that's the key bit there; if you want that amount to be available on other pages, you'll need to store it somewhere (other than in this XML).
XSL is not the right tool for this job.
I'd parse this XML and put its contents in a database.
Then it's simple to write a SQL query that grabs the SUM() of a column