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	$168.65	8.408%	$182.8301	$182.83	$182.85	$182.80
Purchase #2	$29.58	12.478%	$33.271	$33.27	$33.25	$33.30
Purchase #3	$191.72	8.737%	$208.4706	$208.47	$208.45	$208.50
Purchase #4	$149.59	7.282%	$160.4831	$160.48	$160.50	$160.50
Purchase #5	$60.53	9.430%	$66.238	$66.24	$66.25	$66.20
Purchase #6	$121.86	10.186%	$134.2727	$134.27	$134.25	$134.30
Purchase #7	$168.59	10.676%	$186.5887	$186.59	$186.60	$186.60
7 purchase totals =	$890.52		$972.1542	$972.15	$972.15	$972.20