This could have gone in the "small things that make you happy" thread but I think it's better in here.
The other week me and a mate went to see Deadpool. I paid for my tickets and said "thank you very much" with a smile. The girl who served me, well her face lit up. She then said "That's the only time anybody has said thank you to me all day."
Dead chuffed I was, but I was also a little bit sad for the girl in question. Retail in all it's forms is a very challenging job. I know I couldn't do it, and I have the utmost respect for those who do.
So just remember folks: manners cost nothing. And your remarks can literally make or break a person's day. So keep that in mind when handing over your money. You really CAN make a difference to a person's day, or even their life, in some small way.