The question How do I rotate objects? is surprisingly common on Inkscape users’ forums and mailing lists. To rotate the selection, you need to switch the Selector tool into rotate mode, and here’s the little secret of how this switch is done: by a second click on the selection. (Note that this must be a distinct second click, not a quick double-click.) A third click toggles the Selector back into scale mode, a fourth returns it to rotate mode, and so on:
Inkscape didn’t invent this; the separate Selector mode is borrowed from the CorelDRAW and Xara vector editors. Not surprisingly, most of the people who have problems with this convention are accustomed to Adobe Illustrator instead.
There’s one problem with the second click: Just like with moving, it may not always be possible to click the selection without selecting something else (if, for example, selected objects are in groups or under other objects). In these cases, just press to switch to the rotate mode or back.
Once you are in the rotate mode, rotating the selection is as easy as dragging the corner handles. Dragging side handles skews the selection.
When rotating, constrains the rotation angle to equidistant angle increments, by default every 15 degrees:
This constraint angle can be changed in the Steps tab of the Inkscape Preferences dialog (the Rotation snaps every drop-down menu). You can choose one of the many values from 0.5 degrees to 90 degrees.
Skewing with honors the same constraint angle:
-rotation temporarily moves the rotation center to the bounding box corner opposite to that of the corner handle being dragged.