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	$208.42	4.536%	$217.8739	$217.87	$217.85	$217.90
Purchase #2	$50.84	6.110%	$53.9463	$53.95	$53.95	$53.90
Purchase #3	$133.95	6.240%	$142.3085	$142.31	$142.30	$142.30
Purchase #4	$208.46	6.487%	$221.9828	$221.98	$222.00	$222.00
Purchase #5	$123.94	13.561%	$140.7475	$140.75	$140.75	$140.70
Purchase #6	$152.85	13.145%	$172.9421	$172.94	$172.95	$172.90
Purchase #7	$192.51	9.222%	$210.2633	$210.26	$210.25	$210.30
7 purchase totals =	$1,070.97		$1,160.0644	$1,160.06	$1,160.05	$1,160.00