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	$64.81	4.652%	$67.825	$67.83	$67.85	$67.80
Purchase #2	$109.46	4.714%	$114.6199	$114.62	$114.60	$114.60
Purchase #3	$183.93	7.211%	$197.1932	$197.19	$197.20	$197.20
Purchase #4	$21.27	13.800%	$24.2053	$24.21	$24.20	$24.20
Purchase #5	$165.97	5.742%	$175.5	$175.50	$175.50	$175.50
Purchase #6	$182.79	4.817%	$191.595	$191.60	$191.60	$191.60
Purchase #7	$213.81	4.111%	$222.5997	$222.60	$222.60	$222.60
7 purchase totals =	$942.04		$993.5381	$993.55	$993.55	$993.50