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	$105.89	10.628%	$117.144	$117.14	$117.15	$117.10
Purchase #2	$227.46	12.426%	$255.7242	$255.72	$255.70	$255.70
Purchase #3	$109.31	11.113%	$121.4576	$121.46	$121.45	$121.50
Purchase #4	$32.95	8.796%	$35.8483	$35.85	$35.85	$35.80
Purchase #5	$208.68	6.822%	$222.9161	$222.92	$222.90	$222.90
Purchase #6	$132.92	11.620%	$148.3653	$148.37	$148.35	$148.40
Purchase #7	$120.65	3.297%	$124.6278	$124.63	$124.65	$124.60
7 purchase totals =	$937.86		$1,026.0833	$1,026.09	$1,026.05	$1,026.00