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	$65.74	3.369%	$67.9548	$67.95	$67.95	$68.00
Purchase #2	$244.48	7.367%	$262.4908	$262.49	$262.50	$262.50
Purchase #3	$188.38	5.488%	$198.7183	$198.72	$198.70	$198.70
Purchase #4	$41.81	8.522%	$45.373	$45.37	$45.35	$45.40
Purchase #5	$209.38	11.198%	$232.8264	$232.83	$232.85	$232.80
Purchase #6	$224.69	6.196%	$238.6118	$238.61	$238.60	$238.60
Purchase #7	$106.90	5.244%	$112.5058	$112.51	$112.50	$112.50
7 purchase totals =	$1,081.38		$1,158.4809	$1,158.48	$1,158.45	$1,158.50