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	$190.34	5.522%	$200.8506	$200.85	$200.85	$200.90
Purchase #2	$195.89	9.829%	$215.144	$215.14	$215.15	$215.10
Purchase #3	$143.45	12.654%	$161.6022	$161.60	$161.60	$161.60
Purchase #4	$60.69	10.633%	$67.1432	$67.14	$67.15	$67.10
Purchase #5	$195.67	13.435%	$221.9583	$221.96	$221.95	$222.00
Purchase #6	$132.58	10.160%	$146.0501	$146.05	$146.05	$146.10
Purchase #7	$131.53	6.846%	$140.5345	$140.53	$140.55	$140.50
7 purchase totals =	$1,050.15		$1,153.2829	$1,153.27	$1,153.30	$1,153.30