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	$63.57	8.600%	$69.037	$69.04	$69.05	$69.00
Purchase #2	$111.76	10.527%	$123.525	$123.53	$123.55	$123.50
Purchase #3	$206.40	7.647%	$222.1834	$222.18	$222.20	$222.20
Purchase #4	$219.30	12.411%	$246.5173	$246.52	$246.50	$246.50
Purchase #5	$92.63	7.505%	$99.5819	$99.58	$99.60	$99.60
Purchase #6	$15.77	13.406%	$17.8841	$17.88	$17.90	$17.90
Purchase #7	$173.61	7.434%	$186.5162	$186.52	$186.50	$186.50
7 purchase totals =	$883.04		$965.2449	$965.25	$965.30	$965.20