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	$243.86	10.651%	$269.8335	$269.83	$269.85	$269.80
Purchase #2	$18.88	3.471%	$19.5353	$19.54	$19.55	$19.50
Purchase #3	$51.39	6.468%	$54.7139	$54.71	$54.70	$54.70
Purchase #4	$183.90	12.118%	$206.185	$206.19	$206.20	$206.20
Purchase #5	$65.34	9.105%	$71.2892	$71.29	$71.30	$71.30
Purchase #6	$100.95	10.714%	$111.7658	$111.77	$111.75	$111.80
Purchase #7	$29.37	5.211%	$30.9005	$30.90	$30.90	$30.90
7 purchase totals =	$693.69		$764.2232	$764.23	$764.25	$764.20