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	$101.92	9.506%	$111.6085	$111.61	$111.60	$111.60
Purchase #2	$191.81	8.600%	$208.3057	$208.31	$208.30	$208.30
Purchase #3	$181.52	9.356%	$198.503	$198.50	$198.50	$198.50
Purchase #4	$178.77	6.764%	$190.862	$190.86	$190.85	$190.90
Purchase #5	$16.55	3.257%	$17.089	$17.09	$17.10	$17.10
Purchase #6	$63.63	4.692%	$66.6155	$66.62	$66.60	$66.60
Purchase #7	$211.76	9.796%	$232.504	$232.50	$232.50	$232.50
7 purchase totals =	$945.96		$1,025.4877	$1,025.49	$1,025.45	$1,025.50