Calculated columns giving me values to thirteen decimal places

I have some calculated columns in a SharePoint list and a using an InfoPath form to make it look a bit nicer.

The total for each line is based on the uint price multiplied by the quantity. The sub total is the addition of the totals on each line. The grand total is the sub total, plus handling, plus VAT.

Despite each field being set to 2 decimal places, all my totals are to 15 digits, whether it is a 1-digit number with 14 decimal places, or 2-digit with 13 decimal places, etc.

Am I doing something wrong to be getting this result?