Should the true/false rounding depend on whether the focus is before the anchor, or the anchor is before the focus?

E.g., if I select a paragraph from end to beginning, this will round the anchor down, and focus up (correct)
If i then select the same paragraph from beginning to end, this will round the anchor down (into the previous paragraph potentially) and the focus up (into the next paragraph potentially).

This is probably the first place that would really benefit from each point conversion being contained to a node.