They already do this in LA. Get sentenced to 120 days in jail but due to overcrowding you’d do 5-10 days in jail.

Soon local politicians will require you only to do 1% of jail time so you’ll be sentenced to a 100 years in jail for a misdemeanor. This already exists in the California bail system where you pay 1% of astronomically high bails (eg $60,000 bail for 1st time misdemeanor, like if they change a court date and fail to inform you).