Sales tax tokens
From Tax Rates Wiki
Sales tax tokens were created in the early 1900s to resolve the problem of dealing with sales tax and fractions of a cent. Since rounding up was considered unfair practice, the following solution was devised:
Tokens denoting a fraction of a cent called a "mill." A mill equals 1/1000th of a dollar, or 1/10th of 1 cent. Denominations of 1 and 5 were common demonimations. Other denominations were available in some states. Consumers would need to carry these additional coins in order to resolve sales tax fractional requirements.
Sales tax tokens were never instituted by the Federal government because no federal, or national, sales tax was implemented. But when states began implementing sales taxes, and discovered the problem of collecting sales tx on smaller denominations than a dollar, sales tax tokens were created.
States that instituted or minted sales tax tokens include: Alabama, Arizona, Colorado, Illinois, Kansas, Louisiana, Mississippi, New Mexico, Oklahoma, Utah and Washington (courtesy of taxtoken.org )
Sales tax tokens have become a part of the world of coin collecting today.