I first specifically noticed this happening during the Carter administration, in particular with candy bars. The price went from 15 cents to 20 cents, but the candy bars' labels said they were still the same size. Then after awhile they would decrease the size, and the labels would say they were still the same price. They did this repeatedly until they were 50 cents at the end of my store days. I assume the same thing is still happening, but mostly without those signaling labels.