Calm cashier keeps his cool as armed robber threatens him with gun

During an armed robbery at a Jimmy John's, one cashier shockingly kept his cool under extremely stressful circumstances.
The sandwich shop located on 3900 Broadway in Kansas City, Missouri, was held up around 9pm on Wednesday by a man wearing a light blue sweatshirt.
It appears that something another worker said agitated the robber, who pulled a handgun from his sweatshirt and demanded the cashier to empty the register.
In a situation that would generally cause panic, the employee seems completely calm as he removes his plastic gloves, throws them away, then slowly begins stacking up cash to hand to the man.
At one point, the robber can be seen pointing the gun directly at the cashier's head, in the footage obtained by Fox 4 KC.
Commenters online theorized that when the man cocked his gun, he appeared to have jammed it, which would have disabled its ability to fire.
Some speculated that perhaps that was why the cashier seemed unconcerned - if he was aware that he wouldn't have been shot if the robber had tried.
Regardless, his ability to keep his wits about him under the circumstances was surprising to many.
Police are still on the lookout for the man in the light blue sweatshirt, and anyone with information on his whereabouts are encouraged to call the anonymous TIPS Hotline at 816-474-TIPS (8477).