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	$145.68	6.203%	$154.7165	$154.72	$154.70	$154.70
Purchase #2	$150.90	11.614%	$168.4255	$168.43	$168.45	$168.40
Purchase #3	$162.65	10.195%	$179.2322	$179.23	$179.25	$179.20
Purchase #4	$43.90	4.849%	$46.0287	$46.03	$46.05	$46.00
Purchase #5	$68.76	8.509%	$74.6108	$74.61	$74.60	$74.60
Purchase #6	$155.61	11.511%	$173.5223	$173.52	$173.50	$173.50
Purchase #7	$214.33	5.211%	$225.4987	$225.50	$225.50	$225.50
7 purchase totals =	$941.83		$1,022.0347	$1,022.04	$1,022.05	$1,021.90