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	$67.61	7.398%	$72.6118	$72.61	$72.60	$72.60
Purchase #2	$183.67	8.131%	$198.6042	$198.60	$198.60	$198.60
Purchase #3	$33.70	13.568%	$38.2724	$38.27	$38.25	$38.30
Purchase #4	$241.29	6.712%	$257.4854	$257.49	$257.50	$257.50
Purchase #5	$235.87	8.512%	$255.9473	$255.95	$255.95	$255.90
Purchase #6	$132.83	4.725%	$139.1062	$139.11	$139.10	$139.10
Purchase #7	$78.58	5.493%	$82.8964	$82.90	$82.90	$82.90
7 purchase totals =	$973.55		$1,044.9237	$1,044.93	$1,044.90	$1,044.90