Well when are you going to use that loose change? It is a pain to carry around and hear them clink. Its like they are the equivalent to a human cow bell. Nobody wants to be known as a Mr. Krabs. When you actually get to pay with them, it is a pain to have to take your time jumbling around all of the change while people wait on you.
Yes, you can try to predict how much cents you need, but tax will throw you off. My solution to this is get a coin purse with a dollar amount in change. When you buy something for $7.46 you can give them your $2 in change, a Lincoln ($5 bill), and either $1 or two quarters. You will still get change back, but you have less coins than you started with. The other solution is to go up to the cashier and ask them to exchange your coins (or low dollar bills; $1 or $5) for dollars (or $10 or $20). They normally will be glad cause cashiers also have the problem for getting a bunch of paper money ($10, $20, $50, $100) from customers and so they will need some dimes, nickel, and pennies for the change back. It is like the cashier's have the opposite problem than us (even though they rather have $5 and$1 to break the$10, $20, $50, $100, but that is a different story). In the long run this would kill two birds with one stone. My last option is to make a bet and pay the person in change. My sister won a bet, but her friend payed her in $3 worth of pennies. You can't buy anything with 300 pennies!
Also, YouTube & book author, John Green has some good points. It makes no sense/cents (blehhh puns are hard over txt) to make pennies and nickels when they cost twice the price to make them. I hope he doesn't mind me buying my VIDCON ticket in change. :D
(Yah, If you don't know. The Vlogbrothers invented Vidcon.)