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	$242.73	10.262%	$267.639	$267.64	$267.65	$267.60
Purchase #2	$100.88	13.182%	$114.178	$114.18	$114.20	$114.20
Purchase #3	$50.64	7.702%	$54.5403	$54.54	$54.55	$54.50
Purchase #4	$111.48	13.672%	$126.7215	$126.72	$126.70	$126.70
Purchase #5	$81.86	4.614%	$85.637	$85.64	$85.65	$85.60
Purchase #6	$167.98	13.366%	$190.4322	$190.43	$190.45	$190.40
Purchase #7	$207.92	10.553%	$229.8618	$229.86	$229.85	$229.90
7 purchase totals =	$963.49		$1,069.0098	$1,069.01	$1,069.05	$1,068.90