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	$13.26	9.346%	$14.4993	$14.50	$14.50	$14.50
Purchase #2	$40.82	7.790%	$43.9999	$44.00	$44.00	$44.00
Purchase #3	$224.89	13.764%	$255.8439	$255.84	$255.85	$255.80
Purchase #4	$90.82	5.397%	$95.7216	$95.72	$95.70	$95.70
Purchase #5	$115.98	7.153%	$124.276	$124.28	$124.30	$124.30
Purchase #6	$209.93	5.559%	$221.6	$221.60	$221.60	$221.60
Purchase #7	$236.57	12.703%	$266.6215	$266.62	$266.60	$266.60
7 purchase totals =	$932.27		$1,022.5622	$1,022.56	$1,022.55	$1,022.50