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	$248.94	5.556%	$262.7711	$262.77	$262.75	$262.80
Purchase #2	$30.73	4.137%	$32.0013	$32.00	$32.00	$32.00
Purchase #3	$103.74	12.376%	$116.5789	$116.58	$116.60	$116.60
Purchase #4	$189.46	5.768%	$200.3881	$200.39	$200.40	$200.40
Purchase #5	$95.42	8.231%	$103.274	$103.27	$103.25	$103.30
Purchase #6	$76.68	13.338%	$86.9076	$86.91	$86.90	$86.90
Purchase #7	$239.52	11.717%	$267.5846	$267.58	$267.60	$267.60
7 purchase totals =	$984.49		$1,069.5056	$1,069.50	$1,069.50	$1,069.60