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	$96.57	9.622%	$105.862	$105.86	$105.85	$105.90
Purchase #2	$10.52	6.294%	$11.1821	$11.18	$11.20	$11.20
Purchase #3	$156.36	10.587%	$172.9138	$172.91	$172.90	$172.90
Purchase #4	$230.58	5.146%	$242.4456	$242.45	$242.45	$242.40
Purchase #5	$140.69	11.249%	$156.5162	$156.52	$156.50	$156.50
Purchase #6	$201.80	10.428%	$222.8437	$222.84	$222.85	$222.80
Purchase #7	$212.85	5.134%	$223.7777	$223.78	$223.80	$223.80
7 purchase totals =	$1,049.37		$1,135.5411	$1,135.54	$1,135.55	$1,135.50