Related Clues:

• Hamilton bills
• Hamilton commemoratives
• They're a part of every century
• Column in math
• Treasury bills?
• See 66-Across
• Redesigned U.S. currency in 2006
• Easy-to-count groupings
• Cash-register compartment
• Counting intervals, perhaps
• Register section
• Sentence units, often
• Counting intervals, e.g.
• Long periods
• What some candles represent