Hi! I need moral advice!
Firstly some background info: I am a third year computer systems engineering student. I will likely be studying for another 1.5 to 2 years. To pay for uni I have made good use of the New Zealand Government's student loan scheme (which is interest free). I owe nearly $20,000 from borrowing to pay for the course fees. I do work part time so I have a small income.

About 30 min ago I went to the university book shop to buy text books that are highly recommended for my course. I don't live close enough to uni to have the library easily accessible at all hours so this is necessary. As many of you in tertiary education will know, text books are crazy expensive. Two of the books I needed were around NZ$150 (about US$120) and another was NZ$113. There is a small student discount of 10% (as I later found out). I took the books to the counter along with a few pens where the girl there scanned one book, picked up the pens and went to check their price. She added on the pens to the sale and got me to pay. I was charged $136.

At the time I had no idea what sort of discount I would get on the books so I assumed the university must have set it really high or subsidised recommended texts. I later looked at the receipt and saw that the discount was only 10% and the shop assistant only scanned one book. I effectively got NZ$235 (including 10% discount) worth of books for free. Do I take the error in my favour or do I own up?

Discuss.

I would say, rather flimsily, it depends upon the size of the book store from which you purchased. If it's a massive multi-national corporation, I would have really no guilt about denying them a few extra £$€; if it's a family-owned, local bookshop I would probably return them. Same goes for if I know the shop assistant.

If you had noticed it while you were still in the store, then yes, I would say you need to pay for the book. However, you did not know of her error until later and she obviously did not realize it either, so no. She messed up and you believed that you were paying for everything you were purchasing.

I would probably own up to it, but that's only because however much money you will save is not even worth considering against the size of the total debt you will have by the time you get out. Why not do the right thing for an extra .000x% increase in your debt?

MasterOfHisOwnDomain:
I would say, rather flimsily, it depends upon the size of the book store from which you purchased. If it's a massive multi-national corporation, I would have really no guilt about denying them a few extra £$€; if it's a family-owned, local bookshop I would probably return them. Same goes for if I know the shop assistant.

I agree here. One time I was buying printer ink from Staples. One black ink and 4 colored. The colored ink was significantly more expensive than the black ink, but the girl at the register just scanned the black ink 5 times thinking they were all the same. I played ignorant and enjoyed the "discount". Another time at McDonald's my change was supposed to be 8 dollars but the lady mistakenly gave me a 10 and 3 ones instead of a 5. Once again I pretended I didn't notice.

I couldn't care less about ripping McDonald's out of 5 bucks, but later I thought if the employee was going to get in trouble for the error. That made me consider if what I was doing was the right thing to do, so there was something to consider. Whats done is done though.

MasterOfHisOwnDomain:
I would say, rather flimsily, it depends upon the size of the book store from which you purchased. If it's a massive multi-national corporation, I would have really no guilt about denying them a few extra £$€; if it's a family-owned, local bookshop I would probably return them. Same goes for if I know the shop assistant.

The book shop is owned by the student association. They have stores at most of the universities around the country. Most students including me don't like them much because they supply the printed course notes for lectures. They never print enough for all the people enrolled in each paper so they don't end up with any left over in the case someone decides to drop the paper before they buy the notes. They people without course notes after they have sold out have to request another copy to be printed.

A Dominoes cashier essentially paid me £18 to eat a pizza. We both thought I'd paid, so she gave me the change. Turned out my £20 was under the pizza. She didn't notice, so I just left. I don't really feel bad about it as Dominoes is a huge corporation so they won't miss £18, but if it was a small independent place, then yeah, I would have paid.