Step 1: Read the sentence carefully and identify the subject structure.
“Either two nickels or one dime \underline{\hspace{2cm}} in the parking meter.”
Step 2: When subjects are joined by either … or, the verb agrees with the subject closest to it.
Step 3: The subject closest to the verb is one dime, which is singular.
Step 4: Therefore, a singular verb must be used.
Step 5: The correct sentence is:
“Either two nickels or one dime works in the parking meter.”