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	$97.81	10.434%	$108.0155	$108.02	$108.00	$108.00
Purchase #2	$247.27	7.162%	$264.9795	$264.98	$265.00	$265.00
Purchase #3	$177.61	3.859%	$184.464	$184.46	$184.45	$184.50
Purchase #4	$96.49	10.509%	$106.6301	$106.63	$106.65	$106.60
Purchase #5	$93.75	13.442%	$106.3519	$106.35	$106.35	$106.40
Purchase #6	$56.27	5.467%	$59.3463	$59.35	$59.35	$59.30
Purchase #7	$128.51	3.272%	$132.7148	$132.71	$132.70	$132.70
7 purchase totals =	$897.71		$962.5021	$962.50	$962.50	$962.50