Originally Posted by jaromir

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Kenneth Wisniewski and Robert Blattberg at the University of Chicago's Center for Research in Marketing showed that when the price of margarine was lowered from 89 cents to 71 cents, sales volume increased a mere 65%, but when it was lowered from 89 to 69 cents, sales volume increased by 222%"

http://en.wikipedia.org/wiki/Psychological_pricing

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Analysis of two large samples of newspaper price advertising indicates that there is a strong and robust correlation between the use of the 99 price ending and the presence of a low-price appeal such as a claimed discount.
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http://www.sciencedirect.com/science...c17fe88a300634