No small change

We filled up at Engen 1 stop at Harrismith this morning. I was given 4 cents short in my change. When I asked the petrol attendant about this he said the cashier didn't have small change. He saw that I was annoyed. He offered to give me 10 cents out of his own pocket, which of course I didn't take. This isn't about the 4 cents. It's about the principle. How many cars pass through this petrol station every day? If Engen takes an extra 4 cents from every one , they are making quite a tidy illicit profit. This is a business practice that is not honest. I would like to know what your policy is on this.