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	$70.95	8.556%	$77.0205	$77.02	$77.00	$77.00
Purchase #2	$105.38	6.176%	$111.8883	$111.89	$111.90	$111.90
Purchase #3	$204.43	10.170%	$225.2205	$225.22	$225.20	$225.20
Purchase #4	$240.30	10.750%	$266.1323	$266.13	$266.15	$266.10
Purchase #5	$103.59	8.717%	$112.6199	$112.62	$112.60	$112.60
Purchase #6	$247.65	13.414%	$280.8698	$280.87	$280.85	$280.90
Purchase #7	$201.70	10.215%	$222.3037	$222.30	$222.30	$222.30
7 purchase totals =	$1,174.00		$1,296.0550	$1,296.05	$1,296.00	$1,296.00