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	$244.90	8.748%	$266.3239	$266.32	$266.30	$266.30
Purchase #2	$217.59	3.460%	$225.1186	$225.12	$225.10	$225.10
Purchase #3	$218.80	3.144%	$225.6791	$225.68	$225.70	$225.70
Purchase #4	$21.82	13.370%	$24.7373	$24.74	$24.75	$24.70
Purchase #5	$140.26	11.525%	$156.425	$156.43	$156.45	$156.40
Purchase #6	$92.63	13.453%	$105.0915	$105.09	$105.10	$105.10
Purchase #7	$52.60	10.403%	$58.072	$58.07	$58.05	$58.10
7 purchase totals =	$988.60		$1,061.4474	$1,061.45	$1,061.45	$1,061.40