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	$181.84	9.747%	$199.5639	$199.56	$199.55	$199.60
Purchase #2	$119.82	12.369%	$134.6405	$134.64	$134.65	$134.60
Purchase #3	$10.42	7.222%	$11.1725	$11.17	$11.15	$11.20
Purchase #4	$191.89	13.474%	$217.7453	$217.75	$217.75	$217.70
Purchase #5	$155.38	12.204%	$174.3426	$174.34	$174.35	$174.30
Purchase #6	$151.63	3.364%	$156.7308	$156.73	$156.75	$156.70
Purchase #7	$154.52	11.745%	$172.6684	$172.67	$172.65	$172.70
7 purchase totals =	$965.50		$1,066.8640	$1,066.86	$1,066.85	$1,066.80