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	$84.32	5.726%	$89.1482	$89.15	$89.15	$89.10
Purchase #2	$89.94	5.627%	$95.0009	$95.00	$95.00	$95.00
Purchase #3	$34.49	8.175%	$37.3096	$37.31	$37.30	$37.30
Purchase #4	$214.27	4.376%	$223.6465	$223.65	$223.65	$223.60
Purchase #5	$163.76	8.849%	$178.2511	$178.25	$178.25	$178.30
Purchase #6	$245.33	3.536%	$254.0049	$254.00	$254.00	$254.00
Purchase #7	$68.86	11.110%	$76.5103	$76.51	$76.50	$76.50
7 purchase totals =	$900.97		$953.8715	$953.87	$953.85	$953.80