Getting numbers to round up using FormCalc

I'm trying to do a mileage form in LiveCycle. The mileage rate is .505 and the math rounds up fine when an odd number of miles is used (13, 15, 17 etc) ..so, miles x .505 = xx.xx until the user adds a bridge toll then the sum rounds down.

Check out my form and tell me what the heck I'm doing wrong please..
thanks!

http://www.kidango.org/kidango.pdf