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	$118.54	6.627%	$126.3956	$126.40	$126.40	$126.40
Purchase #2	$46.65	5.209%	$49.08	$49.08	$49.10	$49.10
Purchase #3	$239.52	7.815%	$258.2385	$258.24	$258.25	$258.20
Purchase #4	$108.56	4.663%	$113.6222	$113.62	$113.60	$113.60
Purchase #5	$105.66	5.868%	$111.8601	$111.86	$111.85	$111.90
Purchase #6	$157.37	10.725%	$174.2479	$174.25	$174.25	$174.20
Purchase #7	$158.31	8.364%	$171.551	$171.55	$171.55	$171.60
7 purchase totals =	$934.61		$1,004.9953	$1,005.00	$1,005.00	$1,005.00