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	$229.47	10.327%	$253.1674	$253.17	$253.15	$253.20
Purchase #2	$10.45	11.138%	$11.6139	$11.61	$11.60	$11.60
Purchase #3	$96.48	4.557%	$100.8766	$100.88	$100.90	$100.90
Purchase #4	$132.72	12.712%	$149.5914	$149.59	$149.60	$149.60
Purchase #5	$203.71	10.641%	$225.3868	$225.39	$225.40	$225.40
Purchase #6	$128.27	4.422%	$133.9421	$133.94	$133.95	$133.90
Purchase #7	$206.82	13.802%	$235.3653	$235.37	$235.35	$235.40
7 purchase totals =	$1,007.92		$1,109.9435	$1,109.95	$1,109.95	$1,110.00