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	$196.25	13.528%	$222.7987	$222.80	$222.80	$222.80
Purchase #2	$197.85	6.199%	$210.1147	$210.11	$210.10	$210.10
Purchase #3	$16.99	11.721%	$18.9814	$18.98	$19.00	$19.00
Purchase #4	$228.67	13.801%	$260.2287	$260.23	$260.25	$260.20
Purchase #5	$200.78	10.336%	$221.5326	$221.53	$221.55	$221.50
Purchase #6	$99.94	6.828%	$106.7639	$106.76	$106.75	$106.80
Purchase #7	$62.89	12.449%	$70.7192	$70.72	$70.70	$70.70
7 purchase totals =	$1,003.37		$1,111.1392	$1,111.13	$1,111.15	$1,111.10