Follow the step-by instructions in this guide to Rob a Bank without a Keycard Glitch in Roblox Jailbreak.
The first thing you want to do is become a Prisoner and then escape the Prison.
Once you escape and become a Criminal, make your way to where the Jetpack spawns.
Once you have your Jetpack, make your way to the Gun Shop and grab the Shotgun.
Once you have your Jetpack and Shotgun, make your way to the Bank. 
If the Bank is not open, you will need to come back when it is.
When the Bank is open, you can perform the glitch. What you have to do is first change the camera angle of your Shotgun. 
You can enable this by pressing “V”. Next, you have to go up to the door in First Person and look up. 
Now you have to run forward into the door by holding down W and Shift. You will be inside the bank without a Keycard. 
Rob the Bank like normal but without using a Keycard.
Once you have your money, you can explode the door or do the glitch again to get out. 
And just like that, I completed the Bank robbery without a Keycard. 