Here's the long version:
Barry's Tire Tech
Here's the short version:
I don't think tread "roundness" gives you much indication of the rolling resistance of a tire. But I think the UTQG treadwear rating does - lower UTQG treadwear rating = better RR.
But beware when folks claim their fuel economy went down after replacing tires. More tread rubber = more RR, so wornout tires have better fuel economy, all other things being equal.