Im going back to a store because a cashier forgot to scan one of my items and I didn't say anything.
Why didn't you say anything?
I don't see any point of saying anything in this situation.
That's good you're being responsible by going back to the cashier. People make mistakes, and it is wrong to just let things pass by without a word. It is your responsibility as a customer to help out too.
That cashier knew that she forgot to scan my item. I'm going to complain anyway.
You shouldn't complain you should just go back and pay for your item. Everyone makes mistakes and it's good that you are at least going to correct it.