How long do you go to jail for robbery?

Because robbery is a criminal offense, and each state has its own criminal law, the answer to this question depends on the state in which the crime was committed. Additionally, there are numerous details—called “aggravating factors”—that can increase the jail time for committing a robbery. Finally, many states increase the amount of jail time that you can face if the amount that was stolen was large.
For example, in Maine, robbery can be either a Class A or a Class B offense.
Class A robberies result in up to thirty years of jail time and are committed when physical force is used, a bodily injury is intentionally inflicted or attempted on the victim, or when the robbery is committed with a dangerous weapon.
Class B robberies in Maine come with up to ten years in jail and include physical injuries to the victim that were recklessly caused or force that is threatened but not used.
http://www.mainelegislature.org/legis/statutes/17-A/title17-Asec651.html