Tiles selection transformations are quite broken now in 1.3-beta versions. I hope developers will make them possible just like working with ordinary bitmaps. Including rotation, scaling and skewing.
As for Tiles rotation when placing them it would be really useful to have quick way of doing this. Currently you can switch to normal mode, select tile by double click on its grid cell and rotate with normal transformation tool. New tile will be created automatically (in Auto and Stack modes, and in Manual mode you will rotate tile content this way i.e. change tile).