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	$190.81	10.647%	$211.1255	$211.13	$211.15	$211.10
Purchase #2	$217.31	11.116%	$241.4662	$241.47	$241.45	$241.50
Purchase #3	$139.72	4.103%	$145.4527	$145.45	$145.45	$145.50
Purchase #4	$106.90	4.254%	$111.4475	$111.45	$111.45	$111.40
Purchase #5	$185.49	6.157%	$196.9106	$196.91	$196.90	$196.90
Purchase #6	$199.55	9.300%	$218.1082	$218.11	$218.10	$218.10
Purchase #7	$144.63	13.313%	$163.8846	$163.88	$163.90	$163.90
7 purchase totals =	$1,184.41		$1,288.3953	$1,288.40	$1,288.40	$1,288.40