5. The duties and costs prescribed in sections 1, 2 and 3 are adjusted on 1 April of each year, based on the percentage change in the All-Items Consumer Price Index for Canada, for the preceding year. The change is calculated on the basis of the ratio between the index for the preceding year and the index for the year preceding that year. The index for a given year is the average of the monthly indexes published by Statistics Canada. The adjustment rate may not be less than zero.The adjusted duties and costs are rounded off as follows:
(1) where the annual increase resulting from the adjustment is between $0.01 and $0.25, they are increased by $0.25;
(2) where the annual increase resulting from the adjustment is between $0.25 and $0.50, they are increased by $0.50;
(3) where the annual increase resulting from the adjustment is between $0.50 and $1.00, they are increased by $1.00; and
(4) where the annual increase resulting from the adjustment is greater than $1.00,(a) they are reduced to the nearest dollar if they contain a fraction of a dollar less than $0.50; or
(b) they are increased to the nearest dollar if they contain a fraction of a dollar equal to or greater than $0.50.