If you have XCELL on your computer you can have the worksheet operating for you to see what total cost you end up with for various options.
Fill in the actual exhange rates for the day. To add an option, put an "x" in the box after it. Delete the "x" if you don't want the option.
Alternatively you can click "FILE-Save as", and save the file on your computer for off line use. (Works better)
Let me know how you go