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	$59.54	9.103%	$64.9599	$64.96	$64.95	$65.00
Purchase #2	$196.42	5.644%	$207.5059	$207.51	$207.50	$207.50
Purchase #3	$85.87	8.245%	$92.95	$92.95	$92.95	$93.00
Purchase #4	$185.27	9.287%	$202.476	$202.48	$202.50	$202.50
Purchase #5	$215.72	12.532%	$242.754	$242.75	$242.75	$242.80
Purchase #6	$210.95	5.625%	$222.8159	$222.82	$222.80	$222.80
Purchase #7	$83.48	7.325%	$89.5949	$89.59	$89.60	$89.60
7 purchase totals =	$1,037.25		$1,123.0566	$1,123.06	$1,123.05	$1,123.20