Simple Calculator in the cost/income input field

This has been the bane of my life with all financial software (except for Microsoft Money). I have a big receipt and I want to categorise the transactions by type inside the receipt. What I usually do is scan the receipt and then add up the values and then it could be that groceries is 123.44 and cleaning is 55.33. In Microsoft Money (a lot of love for the software) allowed one to input values in the total value to automatically sum it.

Right now to do this, I have to open calculator on the PC and then do the sum and then input the calculated value in the cost bar. If a basic calculator could be added into the cost bar, it could be cool. Perhaps I am the only one that really needs this feature.