Not quite. You pay a bondsman 10%. The bondsman turns around and pays the full bail amount to the court. If you show up, the bondsman gets their money back from the court but keeps your 10% as a fee. If you don't show up to court, the bondsman does not get their money back and is left holding the bag for the other 90% of the bail amount.

If you skip town, you lose the whole bond.

If you use a bondsman, you lose the 10% no matter what. If you use a bondsman and skip town, you're out 10%, and they're out the other 90%. Hence why bondsmen employ bounty hunters.