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	$202.72	5.829%	$214.5365	$214.54	$214.55	$214.50
Purchase #2	$151.54	11.104%	$168.367	$168.37	$168.35	$168.40
Purchase #3	$177.97	8.533%	$193.1562	$193.16	$193.15	$193.20
Purchase #4	$228.88	12.398%	$257.2565	$257.26	$257.25	$257.30
Purchase #5	$100.46	4.810%	$105.2921	$105.29	$105.30	$105.30
Purchase #6	$150.57	13.724%	$171.2342	$171.23	$171.25	$171.20
Purchase #7	$11.95	13.683%	$13.5851	$13.59	$13.60	$13.60
7 purchase totals =	$1,024.09		$1,123.4276	$1,123.44	$1,123.45	$1,123.50