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	$172.37	7.581%	$185.4374	$185.44	$185.45	$185.40
Purchase #2	$126.60	10.255%	$139.5828	$139.58	$139.60	$139.60
Purchase #3	$157.95	5.448%	$166.5551	$166.56	$166.55	$166.60
Purchase #4	$165.55	6.590%	$176.4597	$176.46	$176.45	$176.50
Purchase #5	$12.61	7.810%	$13.5948	$13.59	$13.60	$13.60
Purchase #6	$123.59	8.306%	$133.8554	$133.86	$133.85	$133.90
Purchase #7	$208.46	11.265%	$231.943	$231.94	$231.95	$231.90
7 purchase totals =	$967.13		$1,047.4282	$1,047.43	$1,047.45	$1,047.50