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	$197.73	5.605%	$208.8128	$208.81	$208.80	$208.80
Purchase #2	$11.27	9.567%	$12.3482	$12.35	$12.35	$12.30
Purchase #3	$24.83	10.242%	$27.3731	$27.37	$27.35	$27.40
Purchase #4	$55.73	11.370%	$62.0665	$62.07	$62.05	$62.10
Purchase #5	$100.74	11.628%	$112.454	$112.45	$112.45	$112.50
Purchase #6	$218.63	6.785%	$233.464	$233.46	$233.45	$233.50
Purchase #7	$133.98	7.754%	$144.3688	$144.37	$144.35	$144.40
7 purchase totals =	$742.91		$800.8874	$800.88	$800.80	$801.00