The reason your dialogue sounds robotic - Characters say things to establish plot, People say things because an emotion/s has influenced them to say it.

Late to the thread but here's my attempt at an edit of the posted dialogue:

You: "Hey, can I withdraw a hundred dollars here?"

Cashier: "Absolutely. You want that in tens, twenties?"

You: "If possible, all fives. Costs five for an all day buss pass and they don't do change."

Cashier: "Oh for sure, I'm a bus man myself."

You: "Sometimes it feels like I live on the eleven."

Cashier: "Same. It can be a wild ride. You take it all the way to the expo center?"

You: "The stop past it. Why?"

Cashier: "Apparently there's some black mask wearing goons been runnin' around that neighborhood."

You: "I haven't seen anything that sketchy."

Cashier: "Heard about this morning. Cashiers are the eyes and ears of this town, believe that."

You: "Well damn."

Cashier: "Be safe, my man. Here's your cash."

You: "Thanks."

Cashier: "You bet."

/r/Screenwriting Thread