Actually it was 10, 12, 15, 25, 20, 25, 30, 35, 40, etc. not counting the variant price anomaly.
I'm speaking primarily about DC which went from .15 to .25 for around a year, but gave you an additional 16 pages of golden age, early silver and sometimes never before printed stories for your extra dime.
Marvel went from .15 cents to .25 cents which lasted only a month or two. But, you got an additional 16 pages of new original storyline. I guess they figured that was kind of hectic and costly because they were at twenty cents before you could shake a yellow lamb's tail!