If one line says 50 and another says 50, they only add up when they are the same currency. A bare number with no currency cannot be trusted. Write the currency you actually took.
If you want one number for the whole shop, pick a dollar rate and leave it for the week. That dollar total is so you can decide. Don’t print it on their statement if you deal with them in pounds or pesos. More in two currencies in the book.
