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	$205.56	8.415%	$222.8579	$222.86	$222.85	$222.90
Purchase #2	$242.97	5.571%	$256.5059	$256.51	$256.50	$256.50
Purchase #3	$172.82	3.531%	$178.9223	$178.92	$178.90	$178.90
Purchase #4	$173.28	5.262%	$182.398	$182.40	$182.40	$182.40
Purchase #5	$208.35	6.687%	$222.2824	$222.28	$222.30	$222.30
Purchase #6	$141.39	4.429%	$147.6522	$147.65	$147.65	$147.70
Purchase #7	$149.25	3.120%	$153.9066	$153.91	$153.90	$153.90
7 purchase totals =	$1,293.62		$1,364.5253	$1,364.53	$1,364.50	$1,364.60