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	$178.70	7.472%	$192.0525	$192.05	$192.05	$192.10
Purchase #2	$129.59	10.813%	$143.6026	$143.60	$143.60	$143.60
Purchase #3	$41.35	7.552%	$44.4728	$44.47	$44.45	$44.50
Purchase #4	$125.28	6.786%	$133.7815	$133.78	$133.80	$133.80
Purchase #5	$119.30	4.677%	$124.8797	$124.88	$124.90	$124.90
Purchase #6	$101.92	9.335%	$111.4342	$111.43	$111.45	$111.40
Purchase #7	$100.42	12.846%	$113.32	$113.32	$113.30	$113.30
7 purchase totals =	$796.56		$863.5433	$863.53	$863.55	$863.60