Truffles are all about temperature: cold (butter+chocolate) dealing with hot (hands)
1. Scoop or pipe out blobs. Chill. This gives you a head-start on the shape and if they are all the same size to start out with, minor discrepancies won't be as noticeable. If you scoop, press the truffle into the scoop firmly and scrap against the side of the bowl to get the same amount each time. This starts out with a flat bottom, but when you re-roll, each ball will end up the same size.
1a. The larger the truffle is, the more obvious the non-roundness issue will be. On that note I like 1/2" balls....possibly because the best truffle I ever had was at a fabulous french meal in a tiny cafe in New Jersey. The female chef sent them over at the end of the meal...for free. Two tiny 1/2" truffles rolled in cocoa. Perfectly circular? No. Perfectly wonderful? Yes.
2 Cool down your kitchen. I know...it's cold outside, but you don't want furnace heat adding to the hand heat you already have to deal with.
3. Work with a dozen at a time (leave the others in the frig) and re-roll lightly with your hands. Service gloves will put a bit of insulation between the truffle and your body heat.
4. Cocoa will cover a multitude of sins. So will coating or tempered chocolate. So will paper candy cups.
5. Add some kind of squiggle (possibly in white or milk chocolate) or ground nuts to differentiate various fillings AND distract the eye from perfect orbs.