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	$82.92	3.315%	$85.6688	$85.67	$85.65	$85.70
Purchase #2	$246.47	10.537%	$272.4405	$272.44	$272.45	$272.40
Purchase #3	$168.98	5.675%	$178.5696	$178.57	$178.55	$178.60
Purchase #4	$23.53	6.555%	$25.0724	$25.07	$25.05	$25.10
Purchase #5	$25.29	10.619%	$27.9755	$27.98	$28.00	$28.00
Purchase #6	$222.37	3.677%	$230.5465	$230.55	$230.55	$230.50
Purchase #7	$177.46	10.758%	$196.5511	$196.55	$196.55	$196.60
7 purchase totals =	$947.02		$1,016.8244	$1,016.83	$1,016.80	$1,016.90