Joanne Scarbeary from SageNThymeDesigns says
. . . I have a sales receipt book with carbon copies that I use- only a couple bucks from Office Depot, etc. After the show I usually go back and type all the sales and the means of purchase (credit cards, check, etc) into an Excel Spreadsheet. This is how I double check that all my orders were processes through Square, etc.
I break out the sales tax by city, state, special district as it varies for some of my shows depending on which city I'm in at the event. I'm now starting to track the booth fee and the number of hours I was present at the event so I can have a better understanding of how much money I'm actually making. Sometimes the higher profit shows are NOT the ones where I had the most sales.
^^^^^^^^^^^^^^^^^^^^^
That's exactly what I do.
If I pay cash for the booth, I have an email that shows I was accepted to the event and the event's price. I print out the email(s) and write on it that I paid cash and use that for my payment receipt. I'll have sales receipts for that day showing I made sales, so all of that should be sufficient.
If I pay by check, I make a copy of the check for my records before I mail it.
I especially like paying booth fees with PayPal. I have a record in my email and one in PayPal. :)