Class or Class
Matthew Yglesias, who I like, writes about not picking up pennies and ignoring the price differential when buying a round of drinks. But I did notice his liberal approach to this issue. For him, its all about class:

If you want to find some kind of rationality to penny-ignoring, I think you need to look at it as a means of class-signaling. The richer you are, the less worthwhile it is for you to bend down to pick up change since you have the same 24 hour day as a poor person but the marginal value of money is less. Hence, by ignoring opportunities to recover small sums of money you make yourself appear to be well-off and the appearance of well-offness has a certain value in social terms. Something similar, I think, could be said about ignoring small debts to friends as when you and a friend buy alternate rounds of beer where one person's brew may cost just a bit more than the other's. Failing to demand compensation for, say, a fifty cent price differential gives you a certain aristocratic air as a person "above" such things as concern with money, etc.

I think he is dead wrong on this. I am a take a penny/leave a penny type of person and I think that the carrying cost of a penny, for me, is higher than one cent. But this has always been the case, or at least since gumballs starting costing more that a penny. As for the price differential when buying rounds of drinks, if you want to quibble over quarters and dimes with your buddies, you might find that you have fewer of them over time. (Buddies that is.)

In this case, I guess I agree that it is a class signaling mechanism, although by class I mean this definition: Elegance of style, taste, and manner; which is not the definition he is referring to.