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	$160.54	7.589%	$172.7234	$172.72	$172.70	$172.70
Purchase #2	$238.34	3.517%	$246.7224	$246.72	$246.70	$246.70
Purchase #3	$234.51	7.345%	$251.7348	$251.73	$251.75	$251.70
Purchase #4	$69.65	11.116%	$77.3923	$77.39	$77.40	$77.40
Purchase #5	$46.72	10.523%	$51.6363	$51.64	$51.65	$51.60
Purchase #6	$173.31	10.428%	$191.3828	$191.38	$191.40	$191.40
Purchase #7	$189.87	7.868%	$204.809	$204.81	$204.80	$204.80
7 purchase totals =	$1,112.94		$1,196.4010	$1,196.39	$1,196.40	$1,196.30