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	$158.68	9.556%	$173.8435	$173.84	$173.85	$173.80
Purchase #2	$16.38	10.516%	$18.1025	$18.10	$18.10	$18.10
Purchase #3	$190.58	11.646%	$212.7749	$212.77	$212.75	$212.80
Purchase #4	$225.52	13.570%	$256.1231	$256.12	$256.10	$256.10
Purchase #5	$42.45	12.636%	$47.814	$47.81	$47.80	$47.80
Purchase #6	$122.64	7.545%	$131.8932	$131.89	$131.90	$131.90
Purchase #7	$184.84	13.271%	$209.3701	$209.37	$209.35	$209.40
7 purchase totals =	$941.09		$1,049.9213	$1,049.90	$1,049.85	$1,049.90