If you change the "Rounding" directly in the Time Entry, it does not show the rounded duration in the "Edit" screen (that shows the "actual" duration), but will show in the main Time Entries page.
Note, changing the "Global" rounding will not affect any pre-existing entries. When an entry is created, the settings are stored in that entry so that any future changes to settings will not affect older existing items. So for any existing entries that are not set, you would have to go into each entry and set the Rounding.
