There's not too much you can do to make a day go by faster when working at any job.
I was a cashier myself for 2 years and I hated it too but what I did was I tried engaging in conversations with the customers and that seemed to help time go by much faster and made the job a little less boring.
Some customers liked to talk and engage in conversation while others didn't.
I worked on looking for another job after that and finally after 2 years I landed an office job were I didn't have to stand all day.
Now I have a job where I can sit down and even though it's a bit boring as well it's less boring than the cashier job and I also hated really having to engage with people even though I tried to just to keep from being bored.