This work presents a cooperative yielding maneuver planner that allows automated vehicles circulating inside single-lane roundabouts to create feasible merging gaps for oncoming cars. The maneuver is triggered once its impact on the predicted evolution of the surrounding traffic has been evaluated (and compared with the case where the ego vehicle normally follows the traffic stream) using a simplified microscopic traffic model. The approach is tested in simulation. Results show that the proposed strategy improves traffic coordination performance by up to 8% and the proposed decision-making scheme is flexible and suitable for a wide range of traffic situations.