This is a story that is all about a young man and how he decides to rage against the system in which he finds himself, and which, to a certain extent, controls his life. It is therefore well worth trying to trace the onset of this epiphany and trying to identify what moment provided the catalyst. It appears, if we examine the story carefully, that what was responsible above all was the way in which Lengel spoke to the girls and embarrassed them in front of everybody else. Note what Lengel says and how Sammy comments on it afterwards:
"Girls, I don't want to argue with you. After this come in here with your shoulders covered. It's our policy." He turns his back. That's policy for you. Policy is what the kingpins want. What the otehrs want is juvenile delinquency.
It is this moment that triggers off Sammy's decision to quit and the long, hard road ahead that he will face because of his rejection of what society expects of him. It is directly after this of course that Sammy finds himself still mulling over what he has seen and heard and unable to carry on ringing up the purchases of his customer. Straight after this, Sammy decides to quit.