I always thought you listed the highest only (plus where ever you're working now), since it's generally assumed that if you graduated college that you have some type of high school equivalency, and so on. It's not like being blackboard monitor of your third grade class is going to be needed to break ties.

Plus, there's this wonderful thing called a curriculum vitae that can be provided if asked. Generally speaking, dry cleaners don't care, though, unless they're hiring.