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	$95.60	10.505%	$105.6428	$105.64	$105.65	$105.60
Purchase #2	$132.28	8.308%	$143.2698	$143.27	$143.25	$143.30
Purchase #3	$142.57	12.178%	$159.9322	$159.93	$159.95	$159.90
Purchase #4	$176.79	8.325%	$191.5078	$191.51	$191.50	$191.50
Purchase #5	$191.82	12.738%	$216.254	$216.25	$216.25	$216.30
Purchase #6	$17.96	8.613%	$19.5069	$19.51	$19.50	$19.50
Purchase #7	$172.70	8.392%	$187.193	$187.19	$187.20	$187.20
7 purchase totals =	$929.72		$1,023.3065	$1,023.30	$1,023.30	$1,023.30