When I need to create rounded segments for a wipeout (e.g. round section-bubble), I usually use the POLYGON command and enter 36 sides, snap to the center of the object representing the rounded portion, and use the "Inscribed" option of the polygon.
If I need to create a single round wipeout like a round table or section buble, then great. If the round part needs to represent a fillet on a corner, then I simply trim away the unwanted part and then PEDIT everything together before making a wipeout
