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	$181.28	8.456%	$196.609	$196.61	$196.60	$196.60
Purchase #2	$19.72	7.731%	$21.2446	$21.24	$21.25	$21.20
Purchase #3	$11.78	3.844%	$12.2328	$12.23	$12.25	$12.20
Purchase #4	$15.77	4.390%	$16.4623	$16.46	$16.45	$16.50
Purchase #5	$11.32	9.396%	$12.3836	$12.38	$12.40	$12.40
Purchase #6	$138.80	10.811%	$153.8057	$153.81	$153.80	$153.80
Purchase #7	$128.55	6.234%	$136.5638	$136.56	$136.55	$136.60
7 purchase totals =	$507.22		$549.3018	$549.29	$549.30	$549.30