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	$233.96	12.344%	$262.84	$262.84	$262.85	$262.80
Purchase #2	$136.69	11.713%	$152.7005	$152.70	$152.70	$152.70
Purchase #3	$28.92	13.807%	$32.913	$32.91	$32.90	$32.90
Purchase #4	$217.94	3.275%	$225.0775	$225.08	$225.10	$225.10
Purchase #5	$180.70	6.679%	$192.769	$192.77	$192.75	$192.80
Purchase #6	$145.71	5.827%	$154.2005	$154.20	$154.20	$154.20
Purchase #7	$74.45	5.352%	$78.4346	$78.43	$78.45	$78.40
7 purchase totals =	$1,018.37		$1,098.9351	$1,098.93	$1,098.95	$1,098.90