Boss asks you for currencies of several countries, so you present a table with the data. The easiest way would be to make it in Excel. Then they ask you to keep a record of the currencies they are buying/selling. Again, the easiest database to do that is an Excel file. You have something that works and didn't need the help of anyone to do it.

The important point would be to recognize that when they ask you this for the second or third time it might be time to automatize it.