public static function markup($cost, $total, $round = false)
    {
        // Avoid division by zero
        if ($cost <= 0) {
            return (float)0;
        }

        $quotient   = self::div($total, $cost);
        $difference = self::sub($quotient, 1);
        $product    = self::mul($difference, 100, $round);
        $markup     = $round ? self::round($product) : $product;

        return (float)$markup;
    }