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	$189.59	3.819%	$196.8304	$196.83	$196.85	$196.80
Purchase #2	$83.40	3.333%	$86.1797	$86.18	$86.20	$86.20
Purchase #3	$97.94	13.631%	$111.2902	$111.29	$111.30	$111.30
Purchase #4	$73.31	4.833%	$76.8531	$76.85	$76.85	$76.90
Purchase #5	$175.44	13.829%	$199.7016	$199.70	$199.70	$199.70
Purchase #6	$222.46	13.574%	$252.6567	$252.66	$252.65	$252.70
Purchase #7	$80.65	4.262%	$84.0873	$84.09	$84.10	$84.10
7 purchase totals =	$922.79		$1,007.5990	$1,007.60	$1,007.65	$1,007.70