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	$62.46	4.246%	$65.1121	$65.11	$65.10	$65.10
Purchase #2	$196.73	11.119%	$218.6044	$218.60	$218.60	$218.60
Purchase #3	$233.38	8.604%	$253.46	$253.46	$253.45	$253.50
Purchase #4	$12.81	7.379%	$13.7552	$13.76	$13.75	$13.80
Purchase #5	$225.73	9.185%	$246.4633	$246.46	$246.45	$246.50
Purchase #6	$208.55	4.329%	$217.5781	$217.58	$217.60	$217.60
Purchase #7	$27.85	11.392%	$31.0227	$31.02	$31.00	$31.00
7 purchase totals =	$967.51		$1,045.9958	$1,045.99	$1,045.95	$1,046.10