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	$100.54	5.265%	$105.8334	$105.83	$105.85	$105.80
Purchase #2	$6.30	13.778%	$7.168	$7.17	$7.15	$7.20
Purchase #3	$138.60	5.718%	$146.5251	$146.53	$146.55	$146.50
Purchase #4	$57.26	6.650%	$61.0678	$61.07	$61.05	$61.10
Purchase #5	$47.89	10.707%	$53.0176	$53.02	$53.00	$53.00
Purchase #6	$161.66	9.470%	$176.9692	$176.97	$176.95	$177.00
Purchase #7	$146.73	12.693%	$165.3544	$165.35	$165.35	$165.40
7 purchase totals =	$658.98		$715.9355	$715.94	$715.90	$716.00