Example
Before
Total: $48.00 (tax incl.) Thank you for shopping!
After
Total: $48.00 (tax incl.) Thank you for shopping!
What counts as whitespace
Regular spaces, tabs, and non-breaking spaces, the invisible character that often comes along when you copy from web pages and Word. Line breaks are only removed when you choose “Remove blank lines”, and then only the empty ones.
Two spaces after a period
“Replace repeated spaces with one” also fixes the two-spaces-after-a-period habit, which most current style guides no longer recommend.