You don't have to send flowers, chocolates or a fruit basket - just remember to say thank you. When the interview is over make sure that you shake every one's hand and say thank you. You're thanking them for their time and consideration. A simple thank you will go a long way and exude great manners.
If you find it necessary to do so, you can send a quick thank you note or email. But remember to check your spelling. Also keep in mind due to various legal human resource laws employers can't generally respond to your notes or tokens.