Sooo, I created a SQUARE account and received 2 card readers (I requested 2 because they wear out fast). Now I tell customers right before the ride ends, "There's been some confusion, so I just wanted to let you know that we now have a way to tip your driver, if you want!". If they say "great", I open the SQUARE APP, let them put in the amount and slide their cc. The money goes straight into my bank account. Woo hoo!!!