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	$104.85	11.252%	$116.6477	$116.65	$116.65	$116.60
Purchase #2	$210.32	13.369%	$238.4377	$238.44	$238.45	$238.40
Purchase #3	$66.53	13.787%	$75.7025	$75.70	$75.70	$75.70
Purchase #4	$137.28	4.323%	$143.2146	$143.21	$143.20	$143.20
Purchase #5	$239.54	6.749%	$255.7066	$255.71	$255.70	$255.70
Purchase #6	$50.93	13.147%	$57.6258	$57.63	$57.65	$57.60
Purchase #7	$155.98	11.450%	$173.8397	$173.84	$173.85	$173.80
7 purchase totals =	$965.43		$1,061.1746	$1,061.18	$1,061.20	$1,061.00