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	$196.58	7.169%	$210.6728	$210.67	$210.65	$210.70
Purchase #2	$231.51	10.464%	$255.7352	$255.74	$255.75	$255.70
Purchase #3	$208.52	3.463%	$215.741	$215.74	$215.75	$215.70
Purchase #4	$207.69	5.403%	$218.9115	$218.91	$218.90	$218.90
Purchase #5	$130.47	8.302%	$141.3016	$141.30	$141.30	$141.30
Purchase #6	$10.65	11.782%	$11.9048	$11.90	$11.90	$11.90
Purchase #7	$40.47	4.188%	$42.1649	$42.16	$42.15	$42.20
7 purchase totals =	$1,025.89		$1,096.4318	$1,096.42	$1,096.40	$1,096.40