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	$69.28	4.788%	$72.5971	$72.60	$72.60	$72.60
Purchase #2	$36.48	5.718%	$38.5659	$38.57	$38.55	$38.60
Purchase #3	$83.95	12.466%	$94.4152	$94.42	$94.40	$94.40
Purchase #4	$113.78	12.821%	$128.3677	$128.37	$128.35	$128.40
Purchase #5	$203.51	7.370%	$218.5087	$218.51	$218.50	$218.50
Purchase #6	$66.67	8.662%	$72.445	$72.45	$72.45	$72.40
Purchase #7	$57.36	10.796%	$63.5526	$63.55	$63.55	$63.60
7 purchase totals =	$631.03		$688.4522	$688.47	$688.40	$688.50