variety of different types of expenses, including vacation pay (American Can), interest (Peoples Bank, Mulholland v. U.S., 28 Fed. Cl. 320 (1993), Prabel v. Commissioner, 882 F.2d 820 (3rd Cir. 1989)), customer rebates (Knight Ridder), and related party payables (Bosamia v. Commissioner, 661 F.3d 250