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	$141.31	5.399%	$148.9393	$148.94	$148.95	$148.90
Purchase #2	$190.90	4.584%	$199.6509	$199.65	$199.65	$199.70
Purchase #3	$113.39	5.675%	$119.8249	$119.82	$119.80	$119.80
Purchase #4	$106.81	4.406%	$111.516	$111.52	$111.50	$111.50
Purchase #5	$107.49	4.106%	$111.9035	$111.90	$111.90	$111.90
Purchase #6	$14.90	11.569%	$16.6238	$16.62	$16.60	$16.60
Purchase #7	$217.59	12.481%	$244.7474	$244.75	$244.75	$244.70
7 purchase totals =	$892.39		$953.2058	$953.20	$953.15	$953.10