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	$220.41	11.167%	$245.0232	$245.02	$245.00	$245.00
Purchase #2	$180.31	5.617%	$190.438	$190.44	$190.45	$190.40
Purchase #3	$44.38	10.766%	$49.158	$49.16	$49.15	$49.20
Purchase #4	$156.67	10.411%	$172.9809	$172.98	$173.00	$173.00
Purchase #5	$58.72	13.315%	$66.5386	$66.54	$66.55	$66.50
Purchase #6	$124.54	5.866%	$131.8455	$131.85	$131.85	$131.80
Purchase #7	$175.98	3.692%	$182.4772	$182.48	$182.50	$182.50
7 purchase totals =	$961.01		$1,038.4614	$1,038.47	$1,038.50	$1,038.40