No, we do not really need the penny. Not very many people even use the penny so I do not think it is something we really rely on. Especially since a lot of our money transactions take place digitially. I think we barely even need bills anymore and the world is starting to move more out of that.
Many developed countries are now beginning to get rid of the penny or cent demonination. It is time that the United States followed suit. Not only do people rarely use the penny on a day to day basis, with the rise of debit and credit cards, but it wastes money to produce the coin.
In this day and age, when few people use cash and especially coins anyway, the penny does indeed seem like a useless item. The sellers of goods and services may try to convince consumers that things are cheaper by having a price ending in a penny, but we just wind up with lots of loose change.
I really don't think we need the penny any longer. Inflation has made it obsolete. Several countries, including Canada, have already done away with one cent currencies. Contrary to popular hysterical sentiment, their economy has not imploded under the weight of prices being rounded up or down a few cents.