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	$44.75	3.747%	$46.4268	$46.43	$46.45	$46.40
Purchase #2	$57.43	6.229%	$61.0073	$61.01	$61.00	$61.00
Purchase #3	$64.72	13.619%	$73.5342	$73.53	$73.55	$73.50
Purchase #4	$217.33	13.329%	$246.2979	$246.30	$246.30	$246.30
Purchase #5	$99.47	12.493%	$111.8968	$111.90	$111.90	$111.90
Purchase #6	$163.87	10.118%	$180.4504	$180.45	$180.45	$180.50
Purchase #7	$77.33	12.468%	$86.9715	$86.97	$86.95	$87.00
7 purchase totals =	$724.90		$806.5849	$806.59	$806.60	$806.60