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	$44.41	9.373%	$48.5725	$48.57	$48.55	$48.60
Purchase #2	$116.31	10.329%	$128.3237	$128.32	$128.30	$128.30
Purchase #3	$158.71	6.377%	$168.8309	$168.83	$168.85	$168.80
Purchase #4	$76.65	11.227%	$85.2555	$85.26	$85.25	$85.30
Purchase #5	$207.95	5.143%	$218.6449	$218.64	$218.65	$218.60
Purchase #6	$118.70	10.471%	$131.1291	$131.13	$131.15	$131.10
Purchase #7	$222.64	3.448%	$230.3166	$230.32	$230.30	$230.30
7 purchase totals =	$945.37		$1,011.0732	$1,011.07	$1,011.05	$1,011.00