Good Riddles

Question: Smell me, buy me, and deliver me.
I won't change.

What am I?

Question: If 1/2 of 5 is 3, then what is 1/3 of 10?

Question: What starts with the letter "t", is filled with "t" and ends in "t"?

Question: A man is twenty years old but has only had five birthdays. How is that possible?

Question: what can go up a chimney down but cant go down a chimney up