More than two years now on Square. I total up ALL sales in square, cash or charge. I tell the customer the total and let them decide how to pay.
This will automatically add the Taxes onto my sales for me, and allow me to generate reports when I need to give the state money for sales tax. Cash and credit transactions are all in one place.
I did just request a Paypal here device. not that I don't like square, but so I can sell some bigger items on craigslist, and want to allow people to purchase with a credit card. This way I can keep my accounts separate from Business and personal sales.