Math (Sum) issue in Captivate? Captivate adding additional decimal places and rounding to 10th?

Can someone please help me?  I have a project where the end user will enter check amounts in TEBs, and a running total will display at the bottom of the screen.  However, when I enter 100.17 + 50.00, the running total displays as $150.17000000 versus $150.17. We cannot have extra 0’s display. We must have two decimal places only. I cannot figure out why this is happening or how to control it.  Can someone help?