InfoPath Dev

What I have is the following situation. I have a field that is set to currency but I want to validate that it only accepts numbers and the "$" sign and "," for the 1000 place. But using the following code 
not(xdUtil:Match(string(.), "\d*"))

It does not accept that. Is there a better way to validate the field to only allow numbers or what can I add to this code to make it so that it would work for the currency field. Thank you.

Is your field set to data type currency?

http://office.microsoft.com/en-us/infopath-help/add-or-remove-a-currency-symbol-in-a-text-box-or-expression-box-HP010065296.aspx

I don't believe any additional validation or code is necessary if the data type and format are set up.