Tax calculationAutomatic calculation of price plus tax, price less tax, discount, selling price, tax amount, discount amount, and margin amount. Cost/Sell/MarginCalculate the cost, selling price, or margin of profit on an item, given the other two values. Mark-up/Mark-downAll the mark-up/mark-down capabilities of an adding machine for simplified cost and profit calculations. Key rolloverKey operations are stored in a buffer, so nothing is lost even during high-speed input. Large displayLarge, easy-to-read display. Plastic keysDesigned and engineered for easy operation. 3.5 line-per-second printingThe value indicates the number of lines printed per second.