private function roundDigit( $scale, $mode = PHP_ROUND_HALF_UP )
	{
		if ( $this->getIsCloserToNext( $scale, $mode ) )
		{
			return bcadd( $this->_value, $this->getIsNegative() ? -1 : 1, 0 );
		}

		return bcadd( $this->_value, '0', 0 );
	}