Yes, you can update bids based on your Cost Per Action (CPA) or ROAS (Return on Ad Spending). Steps to bid based on ROI:

for the CPA bidding (Cost per Acquisition/Conversion), it is automatically supported by the PPC BidMax.
Google and Yahoo has their own conversion tracking system in place. If you set them up properly, the information will be downloaded automatically thus, enabling the CPA bidding.

for the ROAS Bidding, since the acquisition of Dynamic Site Stats provider by Yahoo, at the moment, You can use your own 3rd party tracking system. You need to purchase the API documentation of Bid Max and feed your Site Statistical data into Bid Max, so it can change your bids accordingly.

Google and Yahoo FAQ

	Why my position is not showing up on Google Adwords or why the ’Current Position’ is blank?
	How does Bid Max™ control my position on Google Adwords / Yahoo Search Marketing?
	How do I make my ads appear more often?
	How do I autobid more than once per day? I don’t see a value less than 24 hour. What do I do?
	Understand how Bid Max™ works with Google Adwords and Yahoo! Search Marketing
	How quick can Bid Max™ achieve my Target Position?
	My Target Position is #1, I run Bid Max™ once, but it does not change my position to #1, why? (I just start to use Bid Max™ for my Google Adwords and I want to be #1 position. I run the AutoBid, but my ad still stay on #5, why?)
	Most of my keywords have a #1 position before using Bid Max™, after using Bid Max™, some positions have dropped, why?
	How can BidMaximizer save money for me for Google Adwords?
	Is Bid Max™ able to import “Adgroups” into my account? (Or can I create new AdGroups with Bid Max™?)
	What are the advantages of "Bid Max™" ?
	Why is on some of the keywords, the "Current Position" blank ?
	When bidding, can I update bids based on anything other than "position (average/current)" ?
	How to improve your ad quality and optimize your ads?
	How to make sure your keywords are on the first page of Google search?
MORE FAQs