Cummings (BMC) and Ryder Hesjedal (Garmin) made a two-man break and stayed just clear of the peloton, with Cummings outlasting the spent Canadian as they finished 17 and 15 seconds ahead of the peloton respectively.
Hesjedal broke away in the hope of overturning a one minute 26 seconds deficit behind Martin (Omega Pharma-Quick Step) going into the final stage but failed to make serious inroads into the German's lead.
Martin has enjoyed a fruitful 2012, winning the World Time Trial championship, the Tour of Belgium and collecting Time Trial silver at the London Olympics.
Edvald Boasson Hagen (Sky) was the best of the rest finishing third on the stage to clinch the sprint classification.
Andy Schleck (RadioShack Nissan) abandoned after 42km of the stage, which covered 182.5km from Chang Ping to Ping Gu in the Chinese capital.
- Ryder Hesjedal