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	$120.86	10.745%	$133.8464	$133.85	$133.85	$133.80
Purchase #2	$30.95	3.575%	$32.0565	$32.06	$32.05	$32.10
Purchase #3	$187.97	11.774%	$210.1016	$210.10	$210.10	$210.10
Purchase #4	$31.33	10.149%	$34.5097	$34.51	$34.50	$34.50
Purchase #5	$201.55	10.190%	$222.0879	$222.09	$222.10	$222.10
Purchase #6	$144.40	5.615%	$152.5081	$152.51	$152.50	$152.50
Purchase #7	$214.94	6.278%	$228.4339	$228.43	$228.45	$228.40
7 purchase totals =	$932.00		$1,013.5441	$1,013.55	$1,013.55	$1,013.50