A man of modest beginnings, Joe Coyne earned pennies peddling newspapers, lost a job for pitching pennies in the office, and began a career in crime by robbing a cash register stuffed with pennies. Coyne learned to embrace the symbol of his failure, however, and he carved out a corner of the underworld by specializing in penny-themed crimes. He was eventually defeated by Batman, but to this day Batman keeps a gigantic penny in the Batcave as a souvenir of their battle.
During the fight with Bane in the Batcave, the penny was used as a weapon. Bane pushed Batman against the giant penny, causing it to lose balance and fall on top of the hero, causing great damage.
When Nightwing returned to Gotham, he started the reconstruction of the cave along with Alfred and Tim Drake. Robin found the penny laying on one of the deepest and darkest areas of the cave. Using a harness, they lifted the penny to the main area and placed it back on its normal place.
DC Animated Universe
The giant penny was a staple backdrop piece in the Batcave in Batman: The Animated Series. The penny was once a deathrap tool utilized by Two-Face. On one adventure, Two-Face and the "Two-Ton Gang" captured Batman and tied him down to the giant penny. The penny rested on an over-sized coin-flipping machine. Two-Face boasted that if the coin landed on its bad side, then the Batman would be crushed, but even if it landed on its clean side, the impact would break every bone in Batman's body. Two-Face activated the flipping device and the penny sailed through the air. Fortunately, Batman had managed to pilfer Two-Face's lucky coin and used the jagged edges to cut through his ropes. The heavy penny instead landed on two of the villain's fleeing henchmen. 
- The Giant Penny is such a recognised part of the decor of the Batcave that variants on the theme can be found in similar bases: a Giant British Fivepence in the Knight's base, a Giant Wooden Penny in the Bat's Cave, and a giant false coin bearing the motto "In Stagg We Trust" in Batcave West.
- Alfred is the person in charge of polishing the penny and keep it clean.