Why is Penny only a penny?

Not sure if you're serious... 🤔

Like, she should be a Dime or something, maybe even a Nickel

Because her name is definitely not Penny

... seems a lot closer than Nickel..

But sure.. if I think about it now.. 3 Pennys would be appropriate...

It would have to be 1 penny because thats the only coin to say penny on it, the rest say pence. Also 3 pence isn't a coin.