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	$182.79	9.839%	$200.7747	$200.77	$200.75	$200.80
Purchase #2	$239.82	9.306%	$262.1376	$262.14	$262.15	$262.10
Purchase #3	$174.83	12.385%	$196.4827	$196.48	$196.50	$196.50
Purchase #4	$222.40	8.763%	$241.8889	$241.89	$241.90	$241.90
Purchase #5	$54.43	7.398%	$58.4567	$58.46	$58.45	$58.50
Purchase #6	$214.59	5.111%	$225.5577	$225.56	$225.55	$225.60
Purchase #7	$8.56	12.724%	$9.6492	$9.65	$9.65	$9.60
7 purchase totals =	$1,097.42		$1,194.9475	$1,194.95	$1,194.95	$1,195.00