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	$67.35	13.452%	$76.4099	$76.41	$76.40	$76.40
Purchase #2	$162.25	7.494%	$174.409	$174.41	$174.40	$174.40
Purchase #3	$160.60	4.708%	$168.161	$168.16	$168.15	$168.20
Purchase #4	$132.29	12.452%	$148.7628	$148.76	$148.75	$148.80
Purchase #5	$217.91	3.478%	$225.4889	$225.49	$225.50	$225.50
Purchase #6	$22.30	11.344%	$24.8297	$24.83	$24.85	$24.80
Purchase #7	$184.89	6.522%	$196.9485	$196.95	$196.95	$196.90
7 purchase totals =	$947.59		$1,015.0098	$1,015.01	$1,015.00	$1,015.00