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	$199.48	11.725%	$222.869	$222.87	$222.85	$222.90
Purchase #2	$52.79	9.298%	$57.6984	$57.70	$57.70	$57.70
Purchase #3	$217.72	13.419%	$246.9358	$246.94	$246.95	$246.90
Purchase #4	$120.58	6.439%	$128.3441	$128.34	$128.35	$128.30
Purchase #5	$76.85	8.137%	$83.1033	$83.10	$83.10	$83.10
Purchase #6	$108.53	10.169%	$119.5664	$119.57	$119.55	$119.60
Purchase #7	$226.70	5.179%	$238.4408	$238.44	$238.45	$238.40
7 purchase totals =	$1,002.65		$1,096.9578	$1,096.96	$1,096.95	$1,096.90