Lee,
I am a Civil 3D user, and when doing road design sometimes I will use vanilla line work when laying out road profiles, vertical curves and the like.
So, if I want to draw a line at a 2% grade, I set the snapang variable by getting the arctangent of 0.02.
Here is an example:
Command: SNAPANG
Enter new value for SNAPANG <0.0000>: 'cal
>>>> Expression: atan(.02)
Resuming SETVAR command.
Enter new value for SNAPANG <0.0000>: 1.1457628381751