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	$151.60	7.448%	$162.8912	$162.89	$162.90	$162.90
Purchase #2	$17.95	11.707%	$20.0514	$20.05	$20.05	$20.10
Purchase #3	$114.54	7.739%	$123.4043	$123.40	$123.40	$123.40
Purchase #4	$9.86	11.492%	$10.9931	$10.99	$11.00	$11.00
Purchase #5	$146.92	6.222%	$156.0614	$156.06	$156.05	$156.10
Purchase #6	$46.95	10.648%	$51.9492	$51.95	$51.95	$51.90
Purchase #7	$33.45	9.277%	$36.5532	$36.55	$36.55	$36.60
7 purchase totals =	$521.27		$561.9038	$561.89	$561.90	$562.00