Do I need to know exactly how much I paid for books and materials not required?

No, you do not need to know exactly how much you paid for books and materials not required for the Form 1098-T; however, for the American Opportunity Tax Credit, but not the Lifetime Learning Credit, qualified tuition and related expenses include amounts paid for books, supplies and equipment needed for a course of study. You do not have to buy the materials from the eligible educational institution.  So, if you are going to take the American Opportunity Tax Credit, then the amount of your credit could be greater if you if you include the costs of books and materials - in which case you would need to know how much you paid.