rounding and formatting decimals (forced)

I have some embedded data random decimal values that I am using to form my questions. I have them rounded like this:

$$e{ round( e://Field/Savings , 2 ) }

this works great when the values are not divisible by .1, which then will show along the lines of $4.2

Is there any way to format to show 2 decimals, even when the 100's spot is a zero? (would like it to show $4.20)