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	$198.58	4.729%	$207.9708	$207.97	$207.95	$208.00
Purchase #2	$198.87	11.581%	$221.9011	$221.90	$221.90	$221.90
Purchase #3	$135.52	13.544%	$153.8748	$153.87	$153.85	$153.90
Purchase #4	$131.59	8.358%	$142.5883	$142.59	$142.60	$142.60
Purchase #5	$38.29	5.628%	$40.445	$40.45	$40.45	$40.40
Purchase #6	$172.67	5.313%	$181.844	$181.84	$181.85	$181.80
Purchase #7	$143.57	9.228%	$156.8186	$156.82	$156.80	$156.80
7 purchase totals =	$1,019.09		$1,105.4426	$1,105.44	$1,105.40	$1,105.40