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	$116.25	9.866%	$127.7192	$127.72	$127.70	$127.70
Purchase #2	$75.39	4.396%	$78.7041	$78.70	$78.70	$78.70
Purchase #3	$95.85	12.380%	$107.7162	$107.72	$107.70	$107.70
Purchase #4	$106.96	8.705%	$116.2709	$116.27	$116.25	$116.30
Purchase #5	$11.46	5.274%	$12.0644	$12.06	$12.05	$12.10
Purchase #6	$227.77	4.870%	$238.8624	$238.86	$238.85	$238.90
Purchase #7	$19.43	13.341%	$22.0222	$22.02	$22.00	$22.00
7 purchase totals =	$653.11		$703.3594	$703.35	$703.25	$703.40