Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$100.51	4.683%	$105.2169	$105.22	$105.20	$105.20
Purchase #2	$8.69	11.506%	$9.6899	$9.69	$9.70	$9.70
Purchase #3	$217.40	5.438%	$229.2222	$229.22	$229.20	$229.20
Purchase #4	$224.43	13.760%	$255.3116	$255.31	$255.30	$255.30
Purchase #5	$138.30	10.493%	$152.8118	$152.81	$152.80	$152.80
Purchase #6	$244.90	6.525%	$260.8797	$260.88	$260.90	$260.90
Purchase #7	$31.93	11.242%	$35.5196	$35.52	$35.50	$35.50
7 purchase totals =	$966.16		$1,048.6517	$1,048.65	$1,048.60	$1,048.60