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	$216.63	4.219%	$225.7696	$225.77	$225.75	$225.80
Purchase #2	$62.54	7.866%	$67.4594	$67.46	$67.45	$67.50
Purchase #3	$54.45	10.165%	$59.9848	$59.98	$60.00	$60.00
Purchase #4	$153.47	7.716%	$165.3117	$165.31	$165.30	$165.30
Purchase #5	$139.96	4.707%	$146.5479	$146.55	$146.55	$146.50
Purchase #6	$148.99	12.479%	$167.5825	$167.58	$167.60	$167.60
Purchase #7	$160.94	10.449%	$177.7566	$177.76	$177.75	$177.80
7 purchase totals =	$936.98		$1,010.4125	$1,010.41	$1,010.40	$1,010.50