Just about every price label (near me, at least, in all grocery stores) will also include a price-per-quantity. Easy comparison, as long as one isn't measuring containers while another measures ounces.
It is my understanding that this meets the legal requirement, but also satisfies the business desire to confuse the customers trying to make a decision based on the greatest value for money.
I'm in Wisconsin, don't know how other states / nations handle this sort of thing.