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	$10.58	10.585%	$11.6999	$11.70	$11.70	$11.70
Purchase #2	$127.46	10.690%	$141.0855	$141.09	$141.10	$141.10
Purchase #3	$158.65	12.277%	$178.1275	$178.13	$178.15	$178.10
Purchase #4	$158.74	4.533%	$165.9357	$165.94	$165.95	$165.90
Purchase #5	$161.37	8.468%	$175.0348	$175.03	$175.05	$175.00
Purchase #6	$163.26	10.553%	$180.4888	$180.49	$180.50	$180.50
Purchase #7	$148.81	10.326%	$164.1761	$164.18	$164.20	$164.20
7 purchase totals =	$928.87		$1,016.5483	$1,016.56	$1,016.65	$1,016.50