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	$112.42	3.508%	$116.3637	$116.36	$116.35	$116.40
Purchase #2	$131.98	4.167%	$137.4796	$137.48	$137.50	$137.50
Purchase #3	$170.72	8.191%	$184.7037	$184.70	$184.70	$184.70
Purchase #4	$104.62	6.738%	$111.6693	$111.67	$111.65	$111.70
Purchase #5	$220.45	9.301%	$240.9541	$240.95	$240.95	$241.00
Purchase #6	$138.69	13.623%	$157.5837	$157.58	$157.60	$157.60
Purchase #7	$139.28	4.499%	$145.5462	$145.55	$145.55	$145.50
7 purchase totals =	$1,018.16		$1,094.3003	$1,094.29	$1,094.30	$1,094.40