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	$52.36	13.866%	$59.6202	$59.62	$59.60	$59.60
Purchase #2	$213.97	6.314%	$227.4801	$227.48	$227.50	$227.50
Purchase #3	$95.50	6.321%	$101.5366	$101.54	$101.55	$101.50
Purchase #4	$112.83	6.535%	$120.2034	$120.20	$120.20	$120.20
Purchase #5	$43.76	11.275%	$48.6939	$48.69	$48.70	$48.70
Purchase #6	$249.78	9.147%	$272.6274	$272.63	$272.65	$272.60
Purchase #7	$161.37	12.828%	$182.0705	$182.07	$182.05	$182.10
7 purchase totals =	$929.57		$1,012.2321	$1,012.23	$1,012.25	$1,012.20