This attitude is called cash register honesty.
The book store worker knows very well that ball point pens, post-its, copies on the copier machine and long-distance phone calls are office resources and should, in principle, be used only for office purposes.
He is also aware that the he is responsible for his own needs - be it post-its or long-distance phone calls.
By taking some small supplies home or using the office equipment for personal use (e.g. making personal copies or making personal long-distance phone calls), he increases the cost to the company.
Yet, he continues to indulge in the activities described in the question, because he believes, at a personal level, that he can get away with it . (It's okay with him at a personal level.)
However, since stealing from the cash register is not ok with him on a personal level, he doesn't do it even though he knows he can get away with it. This attitude is called cash register honesty.