By all means be discrete. Years ago I worked at A&P stores. As a young collector about the only way I could add to my collection was what coins I received in change. When I got a job at the local grocery, the manager put me on a register right away because I was fast and my drawer was correct every night. I asked the boss if it was O.K. to look at the money in my till to check for ones I needed for my collection. He said sure. Time when on, and a couple of years later I was trying to take a few college courses and work too. Some people can do it, I'm not that good. so I asked for reduced hours. I was stunned. He flew into a rage and berated me for every mistake I had ever made, real and imagined. One of his main beefs was the "fact" I wasted so much time looking at money when I should have been working. I never kept a customer waiting, and I polished my check-out to a shine every time I was working. It really hurt me. I still think about it often to this day because that was my first real job and I admired the man so much. He was an ex-Navy man and kept a military air about him. I learned that no matter what people appear to be and how they act on the outside, they could be exactly the opposite on the inside. That was six years of loyal service wasted because I never got a good work reference from him either. I know the man had problems because he started drinking heavily. I would have to agree he was such a good store manager he should have been promoted. I'm sure that's what he thought too. He would seldom talk to me after that, and being a kid, I thought the problem was mine, not his. As I said the whole situation still bothers me very much. Take heed. be quick and don't talk to your fellow employees about what you are doing. You have acquired some desirable collectible coins so far. Especially considering this is 2017 !
My experience was in the early 1960's when you could get full date early Buffalo nickles, 1916-S 1/2 dollars. 1938-D 1/2 dollars (I found 3 nice ones), Indian Head Cents, all the silver you wanted (who knew?) etc., but I got cheated out of my whole collection a few years later, but that is another story....
Best of luck to you. I am very, very happy to learn a young person is interested in collecting !
Keep looking, you never know what you will find or get in change. 
