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	$200.85	10.567%	$222.0738	$222.07	$222.05	$222.10
Purchase #2	$37.66	8.661%	$40.9217	$40.92	$40.90	$40.90
Purchase #3	$127.66	3.462%	$132.0796	$132.08	$132.10	$132.10
Purchase #4	$98.80	10.353%	$109.0288	$109.03	$109.05	$109.00
Purchase #5	$234.26	4.643%	$245.1367	$245.14	$245.15	$245.10
Purchase #6	$126.81	5.293%	$133.5221	$133.52	$133.50	$133.50
Purchase #7	$140.89	8.783%	$153.2644	$153.26	$153.25	$153.30
7 purchase totals =	$966.93		$1,036.0271	$1,036.02	$1,036.00	$1,036.00