Bottom line: If you have two products you're looking to sell, one higher priced than the other -- price the one that you most want to sell with amount -.99. For instance 2 pens, one $2 and the other $3. If you want to move the $2 pen price it $1.99 and keep the $3 pen at $3.00.
If you want to sell more of the higher priced pen, tag it at $2.99 and the lower priced one at $2.00. If you use .99 cents on both, for instance $1.99 and $2.99, sales will stay flat.
This study was reported on by MarketingProfs who got the information from a study done by The Journal of Consumer Research.
Now, go experiment and let me (and your boss) know about your success.