Can I deduct mandatory class fees under books, materials, and supplies? For example, to take a class I had to pay a set fee of $280, can I deduct this?

[DavidD66]

It is not deductible, but is a qualified expense for determining the Education Credits.

[Hal_Al]

 In general, qualified tuition and related expenses for the education tax credits include tuition and required fees for the enrollment or attendance at eligible post-secondary educational institutions.

Yes, you can enter the fees that were not included in box 1 of the 1098-T, with books required to be purchased from the school. 

Alternatively, you can add then to box 1 of the 1098-T. Underneath box 1, In the 1098-T screen, click on the link "What if this is not what I paid the school" under box 1. You will then be able to enter your actual amounts.