Why were stock prices always multiples of an eighth of a dollar years ago in the US?

Prior to 2001 stock prices where expressed in fractions of 1/8 of a dollar or 12.5 cents. The Securities and Exchange Commission (SEC) changed pricing to the decimal system during 2001 and stocks were thereafter priced in dollars and cents. The SEC made the change to reduce bid and offer spreads on stocks which made pricing more transparent and to reduce the cost of purchases to investors. Stocks had been traded in eighths since the New York Stock Exchange was established and the pricing was based on the Spanish gold currency system which divided gold doubloons into pieces of eight.