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	$212.26	13.590%	$241.1061	$241.11	$241.10	$241.10
Purchase #2	$73.86	11.697%	$82.4994	$82.50	$82.50	$82.50
Purchase #3	$156.46	11.757%	$174.855	$174.86	$174.85	$174.90
Purchase #4	$53.80	10.492%	$59.4447	$59.44	$59.45	$59.40
Purchase #5	$221.77	8.772%	$241.2237	$241.22	$241.20	$241.20
Purchase #6	$177.43	7.584%	$190.8863	$190.89	$190.90	$190.90
Purchase #7	$191.64	7.393%	$205.8079	$205.81	$205.80	$205.80
7 purchase totals =	$1,087.22		$1,195.8231	$1,195.83	$1,195.80	$1,195.80