OK, I have seen adverts for sales that say "Up to half price" and I am not actually sure what they mean!
If they said "up to one third of the price" I would know they mean the price is at most one third of the normal price, i.e. at least two thirds off the normal price.
If they said "up to half off the price" or "up to 50% off [the price]" I would know they mean the price is at least half the normal price, i.e. some price the same as or more than half the normal price. Of course "up to anything off" could in fact be full normal price! Isn't "up to" a lovely phrase...
But what to they mean "up to half price"?
The examples they list on the advert are mostly just under half price, e.g. £299.99 instead of £599.99, so fit perfectly with "up to" meaning "less than or the same as" half the normal price.
But then one is £299.99 instead of £329.99, i.e. nearly 91% of the normal price. Well above half price.
So they have examples that are below half price and above half price. So whatever you think "up to half price" means, they are not actually doing what they say. Trading standards should stop this nonsense.
P.S. The example I am looking at is an Argos advert in a newspaper.