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	$216.50	4.166%	$225.5194	$225.52	$225.50	$225.50
Purchase #2	$214.60	8.578%	$233.0084	$233.01	$233.00	$233.00
Purchase #3	$14.31	4.244%	$14.9173	$14.92	$14.90	$14.90
Purchase #4	$167.27	11.173%	$185.9591	$185.96	$185.95	$186.00
Purchase #5	$104.64	13.331%	$118.5896	$118.59	$118.60	$118.60
Purchase #6	$24.99	11.505%	$27.8651	$27.87	$27.85	$27.90
Purchase #7	$75.26	4.245%	$78.4548	$78.45	$78.45	$78.50
7 purchase totals =	$817.57		$884.3137	$884.32	$884.25	$884.40