It sounds like an error in the instructions - well just because it doesn't sound like the directions are clear. My guess is that selecting tenths allows the program to display the nearest whole number. For example if the grade for Joe is 89.6, the display for Joe is 90, and if the grade for Alice is 89.5, the display for Alice is probably 90 (probably because half-way to 90 from 89, might as well give the 90), and if the grade for Ellen is 89.4, the display is 89. When grades are printed out from highest to lowest, Joe should be listed with 90 before Alice, and Alice with 90, before Ellen who has 89.

Gradebooks customarily round up using the number in the tenths place. For example, an 89.90% and an 89.99% would both round up to an A- as both are greater than or equal to 89.5%. My guess is that the gradebook calculates grades out to the tenths place and then rounds up to the nearest whole number and that rounded number is what is displayed. I think if you were to select hundredths place, it would calculate the grades to said decimal place and then round up to the nearest whole number.