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	$192.56	4.287%	$200.815	$200.82	$200.80	$200.80
Purchase #2	$134.43	6.510%	$143.1814	$143.18	$143.20	$143.20
Purchase #3	$178.86	7.480%	$192.2387	$192.24	$192.25	$192.20
Purchase #4	$57.77	8.399%	$62.6221	$62.62	$62.60	$62.60
Purchase #5	$57.47	13.851%	$65.4302	$65.43	$65.45	$65.40
Purchase #6	$212.52	4.504%	$222.0919	$222.09	$222.10	$222.10
Purchase #7	$199.54	4.602%	$208.7228	$208.72	$208.70	$208.70
7 purchase totals =	$1,033.15		$1,095.1021	$1,095.10	$1,095.10	$1,095.00