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	$62.52	3.623%	$64.7851	$64.79	$64.80	$64.80
Purchase #2	$29.71	7.549%	$31.9528	$31.95	$31.95	$32.00
Purchase #3	$116.72	8.340%	$126.4544	$126.45	$126.45	$126.50
Purchase #4	$40.72	7.730%	$43.8677	$43.87	$43.85	$43.90
Purchase #5	$105.38	13.137%	$119.2238	$119.22	$119.20	$119.20
Purchase #6	$159.49	8.276%	$172.6894	$172.69	$172.70	$172.70
Purchase #7	$181.89	8.144%	$196.7031	$196.70	$196.70	$196.70
7 purchase totals =	$696.43		$755.6763	$755.67	$755.65	$755.80