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	$109.69	4.349%	$114.4604	$114.46	$114.45	$114.50
Purchase #2	$146.48	3.542%	$151.6683	$151.67	$151.65	$151.70
Purchase #3	$246.54	12.129%	$276.4428	$276.44	$276.45	$276.40
Purchase #4	$125.47	11.530%	$139.9367	$139.94	$139.95	$139.90
Purchase #5	$193.29	3.794%	$200.6234	$200.62	$200.60	$200.60
Purchase #6	$64.99	11.554%	$72.4989	$72.50	$72.50	$72.50
Purchase #7	$117.81	7.728%	$126.9144	$126.91	$126.90	$126.90
7 purchase totals =	$1,004.27		$1,082.5449	$1,082.54	$1,082.50	$1,082.50