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	$208.49	9.333%	$227.9484	$227.95	$227.95	$227.90
Purchase #2	$177.40	8.147%	$191.8528	$191.85	$191.85	$191.90
Purchase #3	$46.96	9.683%	$51.5071	$51.51	$51.50	$51.50
Purchase #4	$52.35	3.437%	$54.1493	$54.15	$54.15	$54.10
Purchase #5	$238.56	6.230%	$253.4223	$253.42	$253.40	$253.40
Purchase #6	$116.65	6.661%	$124.4201	$124.42	$124.40	$124.40
Purchase #7	$227.29	12.413%	$255.5035	$255.50	$255.50	$255.50
7 purchase totals =	$1,067.70		$1,158.8035	$1,158.80	$1,158.75	$1,158.70