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	$215.94	13.235%	$244.5197	$244.52	$244.50	$244.50
Purchase #2	$18.59	10.769%	$20.592	$20.59	$20.60	$20.60
Purchase #3	$123.44	12.824%	$139.2699	$139.27	$139.25	$139.30
Purchase #4	$184.52	11.598%	$205.9206	$205.92	$205.90	$205.90
Purchase #5	$32.39	6.542%	$34.509	$34.51	$34.50	$34.50
Purchase #6	$217.42	8.346%	$235.5659	$235.57	$235.55	$235.60
Purchase #7	$153.29	7.170%	$164.2809	$164.28	$164.30	$164.30
7 purchase totals =	$945.59		$1,044.6580	$1,044.66	$1,044.60	$1,044.70