receipt, ticket (fine), coupon [noun] [de bon, de bonnen] ['bon']
"Bon" is typically used for a receipt in a store, and hopefully it will be the common case for you, as opposed to the "ticket" you might get for a traffic offence. The diminutive "bonnetje" is very common in the meaning of "receipt".
Examples:
- "Uw aankoop kan alleen geruild worden binnen 8 dagen met bon."
("Your purchase can only be exchanged within 8 days upon presentation of a receipt." Literally: "… with a receipt.")
- "Wilt u de bon / het bonnetje?"
("Do you want the receipt?")
- "Je moet je bonnnetje goed bewaren, voor het geval dat er iets mis is!"
("You have to hold on to your receipt, in case something is wrong!")
- "U krijgt van mij een bon voor te hard rijden!"
(<police officer:>"I’m giving you a ticket for speeding!" Literally: "… for driving too fast!")
Expressions:
- "Het is op de bon": it is rationed. Used for food, but obviously not in practice anymore in the Netherlands.
- "Op de bon gaan": to be fined, to receive a ticket (for some kind of traffic offence).
- "Op de bon slingeren": to give somebody a fine/ticket. Literally: to sling on the ticket.
Example:
- "Na het beledigen van de agent, werd de man op de bon geslingerd."
("After having insulted the police officer, the man was fined.")
Related words:
- "Waardebon": voucher.
- "Kassabon": cash register slip.
- "Tegoedbon": credit note.
- "Parkeerbon": parking ticket.
- "Boete": fine, penalty.
- "Bonbon": a chocolate, bonbon (taken from the French but can be pronounced the Dutch way).
Extra:
The return policy of purchased goods in the Netherlands is completely customer unfriendly. Usually it has to be returned within 8 days. Often, stores don’t offer refunds, but want to give you a credit note so that they keep the money in house. We think you can actually refuse this, but they will give you a hard time. They will also try to send your DVD recorder off for repairs in the case that you just bought it 2 hours ago and it didn’t work. Of course you must not accept this 
In any case: bewaar altijd je bonnetje!