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	$143.57	8.641%	$155.9759	$155.98	$156.00	$156.00
Purchase #2	$216.78	8.678%	$235.5922	$235.59	$235.60	$235.60
Purchase #3	$12.40	8.653%	$13.473	$13.47	$13.45	$13.50
Purchase #4	$196.80	10.393%	$217.2534	$217.25	$217.25	$217.30
Purchase #5	$67.42	7.852%	$72.7138	$72.71	$72.70	$72.70
Purchase #6	$128.59	11.676%	$143.6042	$143.60	$143.60	$143.60
Purchase #7	$239.75	7.181%	$256.9664	$256.97	$256.95	$257.00
7 purchase totals =	$1,005.31		$1,095.5789	$1,095.57	$1,095.55	$1,095.70