Should the US get rid of the penny?

Yes. I think that's what the study explains in the last paragraph there. The customer is still likely to buy the item if it's ending in $.95 vs $.99. However, as the price of the item goes up, that four cent difference is less important. In the decision making of the buyer, but also costs the company more per unit. It's less important to the business/seller the more expensive it is. I think that's part of the reason they called it a wash.