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	$114.49	8.171%	$123.845	$123.85	$123.85	$123.80
Purchase #2	$159.83	10.674%	$176.8903	$176.89	$176.90	$176.90
Purchase #3	$65.28	8.473%	$70.8112	$70.81	$70.80	$70.80
Purchase #4	$250.54	3.220%	$258.6074	$258.61	$258.60	$258.60
Purchase #5	$163.77	8.660%	$177.9525	$177.95	$177.95	$178.00
Purchase #6	$214.63	6.493%	$228.5659	$228.57	$228.55	$228.60
Purchase #7	$144.71	10.136%	$159.3778	$159.38	$159.40	$159.40
7 purchase totals =	$1,113.25		$1,196.0501	$1,196.06	$1,196.05	$1,196.10