No problems w/ BAII Plus (I have both the plus and the plus professional)... set the format of your calculator to show 6 decimals, rather than the default which is 5. In either case you shouldn't have issues with "excessive" rounding... make sure you set the default number of periods per year to 1... rather than 12 (which is the manufacturer default).
I don't have the CFA text... but computing PV, FV, IRR, NPV... or any other Cash Flow value is very straight forward. Get a handle on this stuff, because you'll be using it to discount cash flows throughout your career. Press your CF key... CF0 is the first cash flow at time 0... press the down arrow key to enter your second cash flow at time 1... press down arrow twice to enter the 3rd cash flow at time 2... and so on. Skip the F1,F2... values... those values allow you to enter the number of periods that your previously entered Cash flow will repeat for. This is in case you have a cash flow that repeats for 10 periods before the next uneven cash flow (at time 11) is expected. Once you've entered all of your cash flows for all of the periods... press your NPV key to enter your interest rate. You have to press the enter key when you enter these values to record them in memory. Press the Compute and the IRR key to compute IRR.
I've heard that CFAI may have a tutorial to help you learn how to use your calculator... good luck...
So you have to change it to suit your needs.