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	$23.26	10.188%	$25.6297	$25.63	$25.65	$25.60
Purchase #2	$244.97	4.147%	$255.1289	$255.13	$255.15	$255.10
Purchase #3	$100.44	11.197%	$111.6863	$111.69	$111.70	$111.70
Purchase #4	$21.87	10.810%	$24.2341	$24.23	$24.25	$24.20
Purchase #5	$86.83	4.158%	$90.4404	$90.44	$90.45	$90.40
Purchase #6	$227.67	8.653%	$247.3703	$247.37	$247.35	$247.40
Purchase #7	$240.79	8.116%	$260.3325	$260.33	$260.35	$260.30
7 purchase totals =	$945.83		$1,014.8222	$1,014.82	$1,014.90	$1,014.70