In some cases when I am justifying a paragraph, the last line is also
justified and if there are only a few words in the line, it looks very
strange with all of the spaces between the words.

However at other times, the last line is unjustified even though the rest of
the paragraph is; so I know there is a way to keep the last line from
justifying but I have been unable to find the propertechnique to do it.