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	$168.55	11.301%	$187.5978	$187.60	$187.60	$187.60
Purchase #2	$59.37	6.660%	$63.324	$63.32	$63.30	$63.30
Purchase #3	$195.31	5.222%	$205.5091	$205.51	$205.50	$205.50
Purchase #4	$56.51	13.371%	$64.066	$64.07	$64.05	$64.10
Purchase #5	$119.66	7.214%	$128.2923	$128.29	$128.30	$128.30
Purchase #6	$214.45	11.345%	$238.7794	$238.78	$238.80	$238.80
Purchase #7	$143.59	7.116%	$153.8079	$153.81	$153.80	$153.80
7 purchase totals =	$957.44		$1,041.3765	$1,041.38	$1,041.35	$1,041.40