a. Amounts derived by persons, other than those engaging in banking, loan, security or other financial businesses, from investments or the use of money as such;

b. Amounts derived from bona fide initiation fees, dues, contributions, donations, tuition fees and endowment funds. The provisions of this subsection shall not be construed to exempt any person, association or society from tax liability upon selling tangible personal property or upon providing facilities or services for which a special charge is made to members or others; provided, that dues which are made for or graduated upon the amount of service rendered by the recipient thereof are not permitted as a deduction hereunder;

c. The amount of cash discount actually taken by the purchaser;

d. The amount of credit losses actually sustained by taxpayers whose regular books of account are kept upon an accrual basis;

e. So much of the sale price of any merchandise sold which is covered by the application to such sale of an allowance for used merchandise at its reasonable value, accepted in lieu of money as a payment on account of the sale. (Ord. M-323, 1956; Ord. M-203 § 8, 1954)