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	$119.47	10.429%	$131.9295	$131.93	$131.95	$131.90
Purchase #2	$21.38	4.408%	$22.3224	$22.32	$22.30	$22.30
Purchase #3	$114.28	10.701%	$126.5091	$126.51	$126.50	$126.50
Purchase #4	$131.93	9.859%	$144.937	$144.94	$144.95	$144.90
Purchase #5	$199.59	7.509%	$214.5772	$214.58	$214.60	$214.60
Purchase #6	$130.61	6.499%	$139.0983	$139.10	$139.10	$139.10
Purchase #7	$41.61	13.795%	$47.3501	$47.35	$47.35	$47.40
7 purchase totals =	$758.87		$826.7236	$826.73	$826.75	$826.70