How to format money / currency variables with commas to two decimal points?

A Money question creates a number-type variable. By default, number-type variables, when interpolated (i.e. displayed on a document or Page Block), are formatted without commas and to a single decimal point. You can change how a number-type variable is formatted by using an Expression Block.

Step 1: Add an Expression Block

Step 2: Select your money variable

Step 3: Use the 'formatted as text with commas to two decimal points' operator

You now have a new variable (the variable created by the Expression Block) that is formatted as you'd expect a money value to be.