Stine was arrested and booked with four misdemeanors including resisting arrest, criminal trespass and disorderly conduct. He was also charged with felony robbery for the incident and is being held on an additional $50,000 bond.
As I understand "being held on an additional $50,000 bond", it means Stine was taken into custody and he would be bailed out after he pays that additional $50,000 bond. Is my understanding to that phrase correct? why is 'on' used? Maybe, it's just an idiomatic usage in that setting and there is no reason for it. I figure "being held over an additional $50,000 bond" probably denotes the same meaning here. I am unsure if "held on" is a set phrase here.
The full source.