def round(self, digits=None):
        """round the geometry."""
        copiedGlyph = self.copyWithoutMathSubObjects()
        # misc
        copiedGlyph.width = _roundNumber(self.width, digits)
        copiedGlyph.height = _roundNumber(self.height, digits)
        # contours
        copiedGlyph.contours = []
        if self.contours:
            copiedGlyph.contours = _roundContours(self.contours, digits)
        # components
        copiedGlyph.components = []
        if self.components:
            copiedGlyph.components = _roundComponents(self.components, digits)
        # guidelines
        copiedGlyph.guidelines = []
        if self.guidelines:
            copiedGlyph.guidelines = _roundGuidelines(self.guidelines, digits)
        # anchors
        copiedGlyph.anchors = []
        if self.anchors:
            copiedGlyph.anchors = _roundAnchors(self.anchors, digits)
        # image
        copiedGlyph.image = None
        if self.image:
            copiedGlyph.image = _roundImage(self.image, digits)
        return copiedGlyph
round the geometry.