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	$161.60	12.485%	$181.7758	$181.78	$181.80	$181.80
Purchase #2	$12.52	3.290%	$12.9319	$12.93	$12.95	$12.90
Purchase #3	$239.98	9.832%	$263.5748	$263.57	$263.55	$263.60
Purchase #4	$106.87	4.711%	$111.9046	$111.90	$111.90	$111.90
Purchase #5	$15.64	5.635%	$16.5213	$16.52	$16.50	$16.50
Purchase #6	$240.42	13.403%	$272.6435	$272.64	$272.65	$272.60
Purchase #7	$151.32	3.807%	$157.0808	$157.08	$157.10	$157.10
7 purchase totals =	$928.35		$1,016.4327	$1,016.42	$1,016.45	$1,016.40