How are you combining dollars and text? Are you combining layout text with a merge field like this?
Some text here <<DollarField>>
If so, you can select the entire text object and select currency formatting in the inspector just like you would for a number field.
the text is a field with calculation if ( field = ""; ""; "say something") - so 2 merge fields together
if ( field = ""; ""; "say something")
But I don't see any numbers to be formatted as currency in your calculation. Where is the number you need to format as currency?
Assuming that such a value is included as part of this calculation, do you really need this to be all in one calculation field? Or could layout text with a merge field do the same thing? Possibly by putting the text as a calculation in one field and the currency in another field?
Otherwise, you have to put together a fairly complex calculation to format the number part of the value returned by your field as currency. (If you have FileMaker Advanced, you may be able to save some trouble if you can find a custom function for this on the Brian Dunning web site of Custom Functions.)