Roundabouts (kikarot) are known to all of us, but the different types are used very freely… I think we can have a better agreement on what to use when.
I am aware of 3 types:
junction=roundabout
This is the more major roundabout, actually a way tagged in addition as ‘highway=residential/tertiary/etc’.
highway=mini_roundabout
This is a minor roundabout, actually a node with this tag. As stated, the mini-roundabout usually does not have an island in the middle but is painted on the road.
highway=turning_circle
This is not quite a roundabout, but rather a wider part at the end of a street, used to ease turning around. As stated, there is no central island/reservation to a turning circle.
Now, the confusing part:
I usually select type 1 for major roads, and type 2 for residential roundabouts. But when there is enough data in residential areas (two oneway parts of a large street, etc), I go for type 1.
The only really painted roundabout I know of (in Israel) is between Yemin Ord and Nir Etzion - here. But it is marked as type 1… Maybe it was changed?
And I never used type 3 until talkat pointed it out to me. It can fit here and here for a start. Please note that in the second link, satellite imagery shows an island in the middle of the turning circle. Still, I think this better fits type 3 than the others.
Therefore I suggest the following:
Use type 1 whenever possible, especially when adding enough details to the map. Even the tiniest roundabout can be drawn as a circular way.
Use type 2 when the roundabout is really painted on the road, or when you are making a rougher sketch (just drawing single ways for wider streets, etc.) The latter case is a transition stage to type 1 roundabout that will be added by the person breaking the single way into two oneway streets, or adding more information in another manner.
Use type 3 at dead-end streets with a widened part at the end (even if there is an island/reservation in the middle).
The mini roundabouts are very very rare in Israel and are normally used if the mapper is a bit lazy to define a correct circle with all exits.
Normally a mini roundabout in Israel means => Please correct me!
Here a typical example : http://www.openstreetmap.org/?lat=32.73337&lon=35.14447&zoom=17&layers=M