Off topic: Do you consider $99 $499 $1999 $99.99 etc. pricing to be unethical?
This pricing technique is just to make someone look.
So, if this is unethical, so is a brightly lit sign, or a couple well-placed adjectives in a sales pitch.
It’s not a significant benefit, restaurants are the best application I can think of, but the harm that occurs from it is similarity miniscule.
Rounding up might be easy. Getting rid through the act of rounding up the instictual psychology that "this is less than the round" is not easy at all, might even be near impossible at the feelings level.