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	$158.85	9.823%	$174.4538	$174.45	$174.45	$174.50
Purchase #2	$150.72	4.255%	$157.1331	$157.13	$157.15	$157.10
Purchase #3	$30.54	3.605%	$31.641	$31.64	$31.65	$31.60
Purchase #4	$237.32	8.109%	$256.5643	$256.56	$256.55	$256.60
Purchase #5	$155.68	10.659%	$172.2739	$172.27	$172.25	$172.30
Purchase #6	$21.60	4.448%	$22.5608	$22.56	$22.55	$22.60
Purchase #7	$236.67	8.323%	$256.368	$256.37	$256.35	$256.40
7 purchase totals =	$991.38		$1,070.9949	$1,070.98	$1,070.95	$1,071.10