5. In the case of an agreement to which regulation 7(1) of the Total Charge for Credit Regulations (agreements under which a period rate of charge is charged) applies, there may be included in a quotation relating to the agreement a rate, being the APR determined as if no account were taken of any amount by which the total amount of the charges included in the total charge for credit in relation to each period is varied so as to bring that amount to the nearest whole penny, one half-penny being for this purpose expressed to the next higher whole penny.