Although many marijuana dealing cases end in probation, there are many people serving jail time and even state prison sentences for selling marijuana. The maximum possible sentence for most marijuana dealing crimes is five years in jail. (35 P.S. 780-113(f)(2)).
However, there is an exception made for cases involving more than One Thousand Pounds of marijuana. In these most serious cases, the maximum penalty is doubled to ten years in jail. (35 P.S. 780-113(f)(1.1)).
As a side note, any time a gun is used in conjunction with a drug dealing situation, there is a five to ten year mandatory sentence. Because the statutory maximum for 99% of marijuana cases is only five years, these cases can end with the very unusual sentence of five years flat. (This is unusual because the minimum and the maximum of the sentence are the same.)