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	$215.93	7.291%	$231.6735	$231.67	$231.65	$231.70
Purchase #2	$217.45	7.824%	$234.4633	$234.46	$234.45	$234.50
Purchase #3	$154.50	7.294%	$165.7692	$165.77	$165.75	$165.80
Purchase #4	$214.59	10.271%	$236.6305	$236.63	$236.65	$236.60
Purchase #5	$137.27	9.839%	$150.776	$150.78	$150.80	$150.80
Purchase #6	$40.30	6.589%	$42.9554	$42.96	$42.95	$43.00
Purchase #7	$49.73	13.854%	$56.6196	$56.62	$56.60	$56.60
7 purchase totals =	$1,029.77		$1,118.8875	$1,118.89	$1,118.85	$1,119.00