No, but why??

they do it because it makes people think it's way cheaper than it actually is, although no one falls for this anymore

also sales tax

true, it's a win-lose for the idiots who fall for it, considering the store pays 0.004c (depending on US state, i am aware you are English, which is around 0.02c if i'm correct), while the person on the losing side thinks they're paying a dollar less than they actually are