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	$208.43	6.500%	$221.978	$221.98	$222.00	$222.00
Purchase #2	$54.51	13.485%	$61.8607	$61.86	$61.85	$61.90
Purchase #3	$160.66	7.414%	$172.5713	$172.57	$172.55	$172.60
Purchase #4	$100.32	6.347%	$106.6873	$106.69	$106.70	$106.70
Purchase #5	$120.79	11.114%	$134.2146	$134.21	$134.20	$134.20
Purchase #6	$91.83	10.626%	$101.5879	$101.59	$101.60	$101.60
Purchase #7	$224.95	12.330%	$252.6863	$252.69	$252.70	$252.70
7 purchase totals =	$961.49		$1,051.5861	$1,051.59	$1,051.60	$1,051.70