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	$173.65	9.814%	$190.692	$190.69	$190.70	$190.70
Purchase #2	$220.33	12.196%	$247.2014	$247.20	$247.20	$247.20
Purchase #3	$161.81	9.280%	$176.826	$176.83	$176.85	$176.80
Purchase #4	$155.86	11.759%	$174.1876	$174.19	$174.20	$174.20
Purchase #5	$82.72	8.636%	$89.8637	$89.86	$89.85	$89.90
Purchase #6	$99.88	13.369%	$113.233	$113.23	$113.25	$113.20
Purchase #7	$152.43	6.123%	$161.7633	$161.76	$161.75	$161.80
7 purchase totals =	$1,046.68		$1,153.7670	$1,153.76	$1,153.80	$1,153.80