So I was at a Tim Hortons buying a large coffee for $1.52. I passed the lady a $5 bill. She then passes me back $18.48 (as if I paid with a $20). I then say no no I gave you a $5. I'll keep this $3.48 and you have the rest. She then continues to pass me an additional $3.48. I then sorted it out and left. Would you keep the money and run or straighten it out?