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	$217.91	8.725%	$236.9226	$236.92	$236.90	$236.90
Purchase #2	$53.88	10.800%	$59.699	$59.70	$59.70	$59.70
Purchase #3	$155.36	4.580%	$162.4755	$162.48	$162.50	$162.50
Purchase #4	$191.27	12.130%	$214.4711	$214.47	$214.45	$214.50
Purchase #5	$210.98	7.236%	$226.2465	$226.25	$226.25	$226.20
Purchase #6	$143.33	7.746%	$154.4323	$154.43	$154.45	$154.40
Purchase #7	$48.72	5.528%	$51.4132	$51.41	$51.40	$51.40
7 purchase totals =	$1,021.45		$1,105.6602	$1,105.66	$1,105.65	$1,105.60