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	$108.75	13.680%	$123.627	$123.63	$123.65	$123.60
Purchase #2	$60.27	13.734%	$68.5475	$68.55	$68.55	$68.50
Purchase #3	$33.72	6.374%	$35.8693	$35.87	$35.85	$35.90
Purchase #4	$210.35	11.132%	$233.7662	$233.77	$233.75	$233.80
Purchase #5	$80.97	5.161%	$85.1489	$85.15	$85.15	$85.10
Purchase #6	$128.62	12.411%	$144.583	$144.58	$144.60	$144.60
Purchase #7	$40.84	3.175%	$42.1367	$42.14	$42.15	$42.10
7 purchase totals =	$663.52		$733.6786	$733.69	$733.70	$733.60