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	$95.88	10.210%	$105.6693	$105.67	$105.65	$105.70
Purchase #2	$98.89	4.527%	$103.3668	$103.37	$103.35	$103.40
Purchase #3	$49.96	7.105%	$53.5097	$53.51	$53.50	$53.50
Purchase #4	$225.84	12.856%	$254.874	$254.87	$254.85	$254.90
Purchase #5	$11.37	8.136%	$12.2951	$12.30	$12.30	$12.30
Purchase #6	$68.44	3.689%	$70.9648	$70.96	$70.95	$71.00
Purchase #7	$49.27	9.526%	$53.9635	$53.96	$53.95	$54.00
7 purchase totals =	$599.65		$654.6432	$654.64	$654.55	$654.80