In the EU, it's a race to the bottom, really. The more type of jobs in the basket, the more possibilities to cheat. The winner is the bidder who gives the lowest offer on all (summa) jobs in the basket. The most used cheat is that you give a relatively high offer on common, often needed jobs, and give an extreme cheap offer on unneeded, 'must-be-there' jobs.
Imagine that there is a basket with color leaflets, color visit cards, color books and a visit card with embossing, foil stamping, spot varnishing. If you give a real-world offer on all of the jobs, you'll surely loose, since the VIP visit card will make your offer (the calculated sum of all the offers on the jobs) too high. There will be another bidder who will offer the VIP card for pennies, 'somehow' knowing that there will be no such visit cards ordered. So the cheater's bid will be lower (and winner), even if the price offered on common jobs is higher.
The only fair game is where they ask for offers on only one kind of job, and they state the copies that will be ordered, for sure. 'Open top' baskets are only up to the industry hawks.