Traditionally, the end is tucked in. However, if you are starting from the bottom, it isn't really necessary. In the days when cotton tape was king, most people taped starting from the top, and tucking in the loose end at the bottom was normal.

If you want to tuck the end in, wrap really hard stretching the tape. This should make it sort of bend in. Cut off excess. Leave maybe 1/4"-3/8" past the end of the bar. Push it in with your finger. Force in the Velox plug. OK to use a mallet. OK to use a little water for lube. Screw it down to hold it.

Occasionally you'll run into a bar that is slightly undersized and/or thicker walled, and a standard velox plug will never fit without sanding or whittling it down a little.