This is the environment implementation of
        :meth:`BaseKerning.round`. **multiple** will be an ``int``.

        Subclasses may override this method.

def _round(self, multiple=1):
        """
        This is the environment implementation of
        :meth:`BaseKerning.round`. **multiple** will be an ``int``.

        Subclasses may override this method.
        """
        for pair, value in self.items():
            value = int(normalizers.normalizeRounding(
                value / float(multiple))) * multiple
            self[pair] = value