With object selected, hit F12
stroke advanced
change corners to round and linetype to round
Set your "contour" using the round outline. Then press Ctrl-Shift-Q and you will now have a vector shape of your outline. Then weld a copy of your original shape to the vector outline.
not sure about X5, but in X4 the option in the Stroke dialog (where you choose how many points thick, etc.) that you're looking for is called "Corners".
Yes, I was aware of that ability/method, but can the rounded contour be done with the "Contour" command (under the "Effects" menu? Using the method with the "Outline" as you've described requires a lot more steps & deleting to get the final desired result.
If you don't want to use a stroke to create the contours you can build your contour and then fillet the corners you want rounded.
Here is what I do. There is a docker called "Fillet/Scallop/Chamfer". It's under "windows" -> "dockers". I leave that docker up on my screen because I use it a lot for all sorts of things.
Simply apply a fillet to your lettering or shape. It can even be a super small radius. THEN do your contour work. Presto rounded contours. The bad part is that you turn your text into curves when you do that.