The judge sets the bail amount during the bail hearing, in setting the bail amount, the judge considers a lot of factors. Some of the factors are severity of the crime, previous convictions, and the ties of the defendant to the community. There is a bail premium which is the fractional amount to be paid to the bail bondsman instead of covering the entire bail amount as set by the court system. The bail bondsman assumes the responsibility of the bail amount and makes sure the defendant goes to the court trials.
If you can notice, there are several states that does not set a specific maximum bail premium but suggest to have an approved rate on file that the bail is not excessive, inadequate and discriminatory. The bail premiums are officially set by the state of Department of Insurance or by the statute. But, you must also be aware that some states does not allow a private bail, to resolve this you must go through the jail systems for bail.
The bail bond rate of the federal courts is set at 15% and 20% is set for the immigration bonds.