Question

In the United States, dollar bills, nickels, and dimes are

Answer 1

dollar bills is a currency
Nickels is 1 cent coin
Dimes is 10 cent coin

Answer 2

The sentence is just left incomplete.

There are no instructions as to what is to be done.

From what is given, it is understood that the sentence may be required to be completed.

So the answer will be In the United States, dollar bills, nickels, and dimes are rates of currencies used for monetary transactions.