1/20 of one cent??

What does it mean when coupons say "cash value 1/20 of one cent" ?? Are there people out there who collect thousands of coupons and turn them in for profit? And, were I one of these persons, who would I go about turning them over to?

Cecil answered this in one of his older books. I couldn't find the link for it though. Basically its to adhere to some laws that these things have to have a cash value and they put it low enough that no one would bother collecting them in order to cash them in.

http://www.straightdope.com/classics/a1_329c.html