Practical experience tells me that's burglary in most jurisdictions. Robbery is when they steal from you face to face. Theft is when they sneak out with stuff without paying for it while the staff is there.
My last game store employer suffered two burglaries (front window bays smashed and looted), one actual robbery (unarmed, and the chump got half a block before staff and two customers tackled him and held him for the cops), and who knows how many thefts (shoplifting, the worst of which was a GW paint set the size of a large suitcase that was behind the counter and eight feet off the floor and my boss still didn't notice it was gone until I got back from the con I was manning a booth at). I missed all the action in every case, and I don't regret it.
The (much smaller) store I was in before that was in a dying mall and the only definite theft we had was a box of Marvel art cards (we did comics too) that some pre-teen lackwit thought we wouldn't notice missing two minutes after it was gone. I put my backup on the counter, strolled out to the front of the mall and found him opening the packs at the bus stop. The police were there in five minutes (dying or not, it was still a mall on a the city's main drag) and marched him back into the store, called his mother away from work, and when she showed up we negotiated an on-the-spot payment for all the (quite expensive) packs he'd wrecked to avoid pressing charges. By the look of terror in the kid's eyes and the mother's facial expression it was probably not the merciful option, and the police knew it as well as I did. Still, can't blame the boss (who wasn't even there, just on the phone) for not wanting to deal with small claims court to get the money, and I wasn't feeling one bit sympathetic for the underage moron at the time.
Not much now, either.
