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	$57.83	7.233%	$62.0128	$62.01	$62.00	$62.00
Purchase #2	$141.73	10.341%	$156.3863	$156.39	$156.40	$156.40
Purchase #3	$113.25	12.477%	$127.3802	$127.38	$127.40	$127.40
Purchase #4	$237.71	6.640%	$253.4939	$253.49	$253.50	$253.50
Purchase #5	$50.96	6.591%	$54.3188	$54.32	$54.30	$54.30
Purchase #6	$207.40	10.456%	$229.0857	$229.09	$229.10	$229.10
Purchase #7	$219.83	7.699%	$236.7547	$236.75	$236.75	$236.80
7 purchase totals =	$1,028.71		$1,119.4324	$1,119.43	$1,119.45	$1,119.50