A calculation device comprises a display including both a first display area and a second display area, and a processor being configured to accept operations of at least one of a tax calculation key which are associated with a plurality of tax rates, respectively, to display, when the operation of the tax calculation key associated with any one of the plurality of tax rates was accepted with respect to numerical value data which indicates tax-excluded amount data displayed on the first display area, tax-included amount data on the first display area, the tax-included amount data being calculated based on the tax rate corresponding to the tax calculation key; and to display, on the second display area, tax-included total amount data which indicates a total of the tax-included amount data corresponding to at least one of the numerical value data.