I forget the specifics now, but you just have to create a helper function that splits each dollar amount into dollars and cents, and returns each in a separate variable. Stick the values into whatever variables you need to get them out.
Create another function to format those values into a string, so it will be "X dollars and Y cents", but so that it will work when either value is 0. And create another function to display those values in the $X.YY format.
Done. But then the hardest part by far is substituting every occurance of "denars" in the module system. Good luck!