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	$204.58	8.801%	$222.5851	$222.59	$222.60	$222.60
Purchase #2	$208.72	10.325%	$230.2703	$230.27	$230.25	$230.30
Purchase #3	$99.57	4.779%	$104.3285	$104.33	$104.35	$104.30
Purchase #4	$191.46	13.663%	$217.6192	$217.62	$217.60	$217.60
Purchase #5	$81.95	5.722%	$86.6392	$86.64	$86.65	$86.60
Purchase #6	$13.58	8.266%	$14.7025	$14.70	$14.70	$14.70
Purchase #7	$141.76	10.654%	$156.8631	$156.86	$156.85	$156.90
7 purchase totals =	$941.62		$1,033.0079	$1,033.01	$1,033.00	$1,033.00