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	$57.25	8.328%	$62.0178	$62.02	$62.00	$62.00
Purchase #2	$191.38	9.350%	$209.274	$209.27	$209.25	$209.30
Purchase #3	$110.72	11.157%	$123.073	$123.07	$123.05	$123.10
Purchase #4	$224.92	12.761%	$253.622	$253.62	$253.60	$253.60
Purchase #5	$194.64	10.675%	$215.4178	$215.42	$215.40	$215.40
Purchase #6	$87.53	13.859%	$99.6608	$99.66	$99.65	$99.70
Purchase #7	$34.51	8.140%	$37.3191	$37.32	$37.30	$37.30
7 purchase totals =	$900.95		$1,000.3845	$1,000.38	$1,000.25	$1,000.40