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	$59.32	5.632%	$62.6609	$62.66	$62.65	$62.70
Purchase #2	$21.25	5.564%	$22.4324	$22.43	$22.45	$22.40
Purchase #3	$169.96	7.575%	$182.8345	$182.83	$182.85	$182.80
Purchase #4	$220.44	10.307%	$243.1608	$243.16	$243.15	$243.20
Purchase #5	$229.40	11.493%	$255.7649	$255.76	$255.75	$255.80
Purchase #6	$241.55	12.756%	$272.3621	$272.36	$272.35	$272.40
Purchase #7	$132.80	6.514%	$141.4506	$141.45	$141.45	$141.50
7 purchase totals =	$1,074.72		$1,180.6662	$1,180.65	$1,180.65	$1,180.80