Why do coupons have a cash value, usually 1/10th of a cent or so? Also, if you really wanted to be a pain in the ass (or had a lot of time on your hands), where would you bring a stack of coupons to redeem their “cash value?”
The Man himself covered this one:
Why do grocery store coupons say “cash value 1/20 of a cent”?
The gist:
Sorry about that, didn’t see his column. 
Heh. I have a friend who’s like that. I mean, in this context to quote sethdallob, a ‘pain in the ass’. If a cashier hands her a Canadian penny, she demands it be exchanged for an American one. Hey, them canadian ones are worth less, after all!
Try it someday. Just to piss off the cashier at the grocery store. 
~Shatz
In an age where the cost of everything goes up, the cash value of coupons has actually gone down. Used to be not so unusual to find ones that said they were worth 1/10 or 1/20 of one cent. Now they’re usually worth 1/100 of a cent.
My question is, is it legal to claim something has a theoretical vaule of next to zip- thousandths or millionths of a cent? It reminds me of some jokers who tried to sell square-inch plots of land-I believe that was eventually ruled fraudulent. After all, the US mint has never been authorized to produce anything smaller than a mill (1/10 cent.) Therefore, is that the “quantum” of money recognized by US jurisprudence?
I know it’s not exactly on point, but here is Cecil’s discussion of the “mill.”
http://www.straightdope.com/classics/a1_336b.html
Cecil’s language is a little oblique, but I think he is saying that the mill is, under U.S. law, “the lowest money of accompt, of which 1,000 shall be equal to the federal dollar, or money unit”
So that would be the “quantum” of money.
Just thought I’d throw my two cents in 