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	$240.32	9.321%	$262.7202	$262.72	$262.70	$262.70
Purchase #2	$160.69	4.215%	$167.4631	$167.46	$167.45	$167.50
Purchase #3	$97.80	6.845%	$104.4944	$104.49	$104.50	$104.50
Purchase #4	$63.82	5.815%	$67.5311	$67.53	$67.55	$67.50
Purchase #5	$126.82	13.255%	$143.63	$143.63	$143.65	$143.60
Purchase #6	$176.49	3.188%	$182.1165	$182.12	$182.10	$182.10
Purchase #7	$86.89	10.109%	$95.6737	$95.67	$95.65	$95.70
7 purchase totals =	$952.83		$1,023.6290	$1,023.62	$1,023.60	$1,023.60