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	$209.30	6.478%	$222.8585	$222.86	$222.85	$222.90
Purchase #2	$15.51	10.634%	$17.1593	$17.16	$17.15	$17.20
Purchase #3	$228.32	5.313%	$240.4506	$240.45	$240.45	$240.50
Purchase #4	$229.89	6.358%	$244.5064	$244.51	$244.50	$244.50
Purchase #5	$170.97	4.735%	$179.0654	$179.07	$179.05	$179.10
Purchase #6	$81.67	6.235%	$86.7621	$86.76	$86.75	$86.80
Purchase #7	$32.63	5.643%	$34.4713	$34.47	$34.45	$34.50
7 purchase totals =	$968.29		$1,025.2736	$1,025.28	$1,025.20	$1,025.50