Yes, feed rate is units per minute.
However, it isn't necessarily the number of decimal places that you should be concerned with, motion controller wise. In the end, a trajectory is boiled down to the number of counts/steps the motor should move in a window of time. The most common "time slice" is 1 millisecond. I don't know what motion controller you are using, so I can't give any advice on what it may or may not do.
For the purposes of this discussion, let's assume that is is running a 1 millisecond time slice. To get continuous motion on the motor, a minimum of 1 count per time slice is needed. Say the counts per unit is 10000 (inch).
10000 per inch == .0001" per millisecond.
.0001 * 1000 == .1000" per second
.1000 * 60 == 6.000" per minute.
That is for the case of each time slice moving 1 count per millisecond. Obviously, the more counts per unit (higher resolution), the slower you can go with the smoothest possible motion. But for most things, we have to compromise on the smoothness of the motion to go slower. Say like a count every other millisecond (3.0000" per minute). The time the motor spent moving would be equal to the time the motor wasn't moving. In other words, 1/2 of the time, the motor would move. But if you extend that out to a count every 4 milliseconds (1.5000" per minute), the motor is moving 1/4 of the time. And so on and so forth. At what point does the motion controller consider the motion as stopped? No movement in 10 milliseconds? 20? 100? That is what you have to worry about.
Steve