He took money from me

This is probably in the wrong topic but...

Ok so I know this is probably not a big deal but I’m on a very tight budget right now because baby #1 is on the way. But I went to the dollar store to pick up 3 things of candy because my hormonal ass craves everything. It was $3.09 and I gave the cashier $3.10. Three bucks and a dime. The guy was literally about to give me my penny but took it back and said “ you don’t need this.” Like what I reached for it but he wouldn’t give it to me. I know it’s just a penny but I keep every single penny... even the ones I find on the dirty bathroom floor. Like I said I’m very tight on money right now. Was it ok for the cashier to keep my penny without me saying keep it? It’s been bugging me lately and I don’t know why. Someone help please!