He probably got the impression that you were scared, and maybe a pushover. And, he was right. He got money out of you. And he will be in that spot more often now, because that spot makes money.

Next time, don't break stride, confidently and firmly and immediately (but not necessarily loudly) say "I don't carry cash" and ignore every word that comes out of their mouth. If he follows you, make sure he thinks you're a crazy SOB that might cut him, and make sure he's aware that you're subtly watching him. Make it so he feels like it's a smaller risk to hassle someone else. Someone else who seems scared or weak.

Let us know if you have any other questions.

We're all in this together.