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	$172.84	12.572%	$194.5694	$194.57	$194.55	$194.60
Purchase #2	$217.91	6.853%	$232.8434	$232.84	$232.85	$232.80
Purchase #3	$80.94	11.873%	$90.55	$90.55	$90.55	$90.60
Purchase #4	$191.27	4.841%	$200.5294	$200.53	$200.55	$200.50
Purchase #5	$75.56	4.113%	$78.6678	$78.67	$78.65	$78.70
Purchase #6	$159.41	8.210%	$172.4976	$172.50	$172.50	$172.50
Purchase #7	$58.66	9.209%	$64.062	$64.06	$64.05	$64.10
7 purchase totals =	$956.59		$1,033.7196	$1,033.72	$1,033.70	$1,033.80