muriatic acid and septic system

Is it OK to use muriatic acid to clean toilet a bowls jets that is discharging into a septic system?

No do not use muriatic acid if you are on a septic tank. The acid will kill the bacteria in the tank.
Muriatic acid should NEVER be poured down a storm drain, a sink or flushed down a toilet. It can cause extreme damage to pipes, dissolve solder and damage the biological balance of your septic system.