protected function validateTotalOrder()
    {
        $field = 'total';
        $value = $this->getSubmitted($field);

        if (!isset($value)) {
            $this->unsetSubmitted($field);
            return null;
        }

        $label = $this->translation->text('Total');

        if (!is_numeric($value)) {
            $this->setErrorNumeric($field, $label);
            return false;
        }

        if (strlen($value) > 10) {
            $this->setErrorLengthRange($field, $label, 0, 10);
            return false;
        }

        return true;
    }