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	$164.52	5.675%	$173.8565	$173.86	$173.85	$173.90
Purchase #2	$166.75	3.286%	$172.2294	$172.23	$172.25	$172.20
Purchase #3	$188.59	9.736%	$206.9511	$206.95	$206.95	$207.00
Purchase #4	$54.45	12.619%	$61.321	$61.32	$61.30	$61.30
Purchase #5	$160.79	10.496%	$177.6665	$177.67	$177.65	$177.70
Purchase #6	$142.89	11.221%	$158.9237	$158.92	$158.90	$158.90
Purchase #7	$55.34	13.266%	$62.6814	$62.68	$62.70	$62.70
7 purchase totals =	$933.33		$1,013.6296	$1,013.63	$1,013.60	$1,013.70