For whatever strange reason, AdWords will give you ROAS (return on ad spend) in the Reporting Center, but not in the Campaign Summary interface. If you’re doing lead generation and cost per conversion is your KPI, that’s easier- ads and keywords have that. But if ROAS is your metric and you need to also consider the average sale for ads and keywords (part of ROAS), you have to run reports in the Reporting Center.

Note, you have to set up your conversion tracking code to pass the sale amount through your form/checkout’s variable to AdWords if you want the sale amount and ROAS metrics. This isn’t always a lot of fun to do if you have to go through a third party, but be annoying- it’s critical.