矮油，你是“折扣党”吧？碰到1块9毛9，就坚决不买2块的。但从质量上考虑，你会不会觉得2块得东西会比“1块9毛9”的东西好呢？

“Economics: supply and demand.”

That’s Father Guido Sarducci...

“That’s it.”

…sharing the entirety of the economics course at his Five-Minute-University. Of course, the market forces of supply and demand are supposed to be the main factors in setting the prices for goods and services. But marketing comes into play as well. Supply and demand have little to do with a seller’s decision to price an item at $19.99 instead of 20 bucks.

The psychological trick of seeing a one instead of a two at the front of a price, as in $19.99 versus $20 can work to increase sales. But Robert Schindler, professor of Marketing at Rutgers School of Business-Camden, says that in some cases, the penny saved isn’t worth it.

The $19.99 technique may actually backfire when a consumer is most concerned about quality, say, in a luxury item. The penny-lower price can then raise questions in the buyer’s mind about quality. According the Schindler, in those cases, the full, round non-99 price may send a signal of a better buy.

—Steve Mirsky