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	$96.80	5.184%	$101.8181	$101.82	$101.80	$101.80
Purchase #2	$59.72	4.635%	$62.488	$62.49	$62.50	$62.50
Purchase #3	$168.72	8.163%	$182.4926	$182.49	$182.50	$182.50
Purchase #4	$48.74	10.576%	$53.8947	$53.89	$53.90	$53.90
Purchase #5	$196.95	9.342%	$215.3491	$215.35	$215.35	$215.30
Purchase #6	$214.55	4.444%	$224.0846	$224.08	$224.10	$224.10
Purchase #7	$153.42	13.206%	$173.6806	$173.68	$173.70	$173.70
7 purchase totals =	$938.90		$1,013.8077	$1,013.80	$1,013.85	$1,013.80