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	$57.56	7.457%	$61.8522	$61.85	$61.85	$61.90
Purchase #2	$76.83	5.239%	$80.8551	$80.86	$80.85	$80.90
Purchase #3	$133.69	8.147%	$144.5817	$144.58	$144.60	$144.60
Purchase #4	$141.71	8.228%	$153.3699	$153.37	$153.35	$153.40
Purchase #5	$188.95	5.661%	$199.6465	$199.65	$199.65	$199.60
Purchase #6	$158.33	9.410%	$173.2289	$173.23	$173.25	$173.20
Purchase #7	$75.71	8.205%	$81.922	$81.92	$81.90	$81.90
7 purchase totals =	$832.78		$895.4563	$895.46	$895.45	$895.50