To the original poster don't let this steer you away from software. All you need to do is grab a piece of tube, make some marks on it for where you stick it in the die of your bender and bend a 90* bend.
Then you take some after measurements and punch them into the software to help it calibrate to YOUR specific setup. Your bender, die and methods of measuring are going to be different than the next guy so this is a good thing that they allow you to calibrate the software.
What it's really trying to do is figure out how much material is "sucked up" for each degree of bend in a given die (or more realistically I'm sure it's working in tenths or hundredths of degrees) as well as calculate a "spring back". The material relaxes and doesn't stay put when you remove it from the die. Every setup is different but you can get this pretty well dialed in on the software or just know your own setup. I know if I go about 2-3* past what I want on my 1-3/4" die it'll relax back to what I really want. No biggie, we crash through rocks not go to the moon.
Anywhoo, just wanted to clarify this process. Sure you "waste" a small piece of tube ONE time but theoretically it'll be the last tube you waste. Plus who can't find a use for a scrap piece of tube bent in a 90*?