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	$169.76	3.364%	$175.4707	$175.47	$175.45	$175.50
Purchase #2	$229.38	9.846%	$251.9648	$251.96	$251.95	$252.00
Purchase #3	$100.82	4.732%	$105.5908	$105.59	$105.60	$105.60
Purchase #4	$243.52	13.688%	$276.853	$276.85	$276.85	$276.90
Purchase #5	$146.54	8.613%	$159.1615	$159.16	$159.15	$159.20
Purchase #6	$184.73	10.453%	$204.0398	$204.04	$204.05	$204.00
Purchase #7	$154.83	3.680%	$160.5277	$160.53	$160.55	$160.50
7 purchase totals =	$1,229.58		$1,333.6083	$1,333.60	$1,333.60	$1,333.70