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	$204.42	6.427%	$217.5581	$217.56	$217.55	$217.60
Purchase #2	$18.60	4.631%	$19.4614	$19.46	$19.45	$19.50
Purchase #3	$226.73	5.533%	$239.275	$239.28	$239.30	$239.30
Purchase #4	$154.90	11.642%	$172.9335	$172.93	$172.95	$172.90
Purchase #5	$184.54	6.659%	$196.8285	$196.83	$196.85	$196.80
Purchase #6	$153.27	7.551%	$164.8434	$164.84	$164.85	$164.80
Purchase #7	$65.44	3.251%	$67.5675	$67.57	$67.55	$67.60
7 purchase totals =	$1,007.90		$1,078.4674	$1,078.47	$1,078.50	$1,078.50