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	$156.30	4.237%	$162.9224	$162.92	$162.90	$162.90
Purchase #2	$43.43	11.622%	$48.4774	$48.48	$48.50	$48.50
Purchase #3	$153.58	5.661%	$162.2742	$162.27	$162.25	$162.30
Purchase #4	$185.52	12.587%	$208.8714	$208.87	$208.85	$208.90
Purchase #5	$146.43	9.464%	$160.2881	$160.29	$160.30	$160.30
Purchase #6	$13.36	3.336%	$13.8057	$13.81	$13.80	$13.80
Purchase #7	$249.95	6.521%	$266.2492	$266.25	$266.25	$266.20
7 purchase totals =	$948.57		$1,022.8884	$1,022.89	$1,022.85	$1,022.90