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	$95.54	13.402%	$108.3443	$108.34	$108.35	$108.30
Purchase #2	$9.82	13.608%	$11.1563	$11.16	$11.15	$11.20
Purchase #3	$97.59	3.385%	$100.8934	$100.89	$100.90	$100.90
Purchase #4	$127.43	13.603%	$144.7643	$144.76	$144.75	$144.80
Purchase #5	$44.59	9.613%	$48.8764	$48.88	$48.90	$48.90
Purchase #6	$203.98	8.832%	$221.9955	$222.00	$222.00	$222.00
Purchase #7	$102.49	8.841%	$111.5511	$111.55	$111.55	$111.60
7 purchase totals =	$681.44		$747.5813	$747.58	$747.60	$747.70