How to display a result with decimal and currency

I've tried everything from the forum and help files. The Masking widget works if it's only user input, and it shows a $ and 00.00. But it won't take calculations. I'm performing calculations. If I use the numbers format for a cell, I get the correct calculation, but I can't add a prefix or decimals. How do I achieve this seemingly simple but impossible task? 

You can use a form calculation field. Search for it on the widgets tab.

How-to-Perform-Form-Calculation-Using-a-Widget

Note: When you add your field to the widget you can prefix it with a $ character (click on it so it turns brown). Or append a % character (again click on it so it turns brown. The reason is that when its brown it is treated as a text string. Whereas if its black it is numeric and used in calculations)

Here's a demo I made:

Demo here:

https://form.jotform.com/80386757828978