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	$177.94	10.451%	$196.5365	$196.54	$196.55	$196.50
Purchase #2	$12.28	4.479%	$12.83	$12.83	$12.85	$12.80
Purchase #3	$213.27	6.462%	$227.0515	$227.05	$227.05	$227.10
Purchase #4	$133.82	4.618%	$139.9998	$140.00	$140.00	$140.00
Purchase #5	$43.76	10.580%	$48.3898	$48.39	$48.40	$48.40
Purchase #6	$51.26	7.459%	$55.0835	$55.08	$55.10	$55.10
Purchase #7	$109.65	6.301%	$116.559	$116.56	$116.55	$116.60
7 purchase totals =	$741.98		$796.4501	$796.45	$796.50	$796.50