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	$204.47	4.731%	$214.1435	$214.14	$214.15	$214.10
Purchase #2	$190.42	5.189%	$200.3009	$200.30	$200.30	$200.30
Purchase #3	$80.63	6.458%	$85.8371	$85.84	$85.85	$85.80
Purchase #4	$195.85	13.153%	$221.6102	$221.61	$221.60	$221.60
Purchase #5	$65.54	4.447%	$68.4546	$68.45	$68.45	$68.50
Purchase #6	$69.48	12.698%	$78.3026	$78.30	$78.30	$78.30
Purchase #7	$203.69	5.628%	$215.1537	$215.15	$215.15	$215.20
7 purchase totals =	$1,010.08		$1,083.8026	$1,083.79	$1,083.80	$1,083.80