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	$92.30	3.574%	$95.5988	$95.60	$95.60	$95.60
Purchase #2	$159.75	3.314%	$165.0441	$165.04	$165.05	$165.00
Purchase #3	$146.62	3.385%	$151.5831	$151.58	$151.60	$151.60
Purchase #4	$29.69	10.787%	$32.8927	$32.89	$32.90	$32.90
Purchase #5	$30.40	6.195%	$32.2833	$32.28	$32.30	$32.30
Purchase #6	$113.28	4.390%	$118.253	$118.25	$118.25	$118.30
Purchase #7	$112.30	10.204%	$123.7591	$123.76	$123.75	$123.80
7 purchase totals =	$684.34		$719.4141	$719.40	$719.45	$719.50