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	$207.67	9.475%	$227.3467	$227.35	$227.35	$227.30
Purchase #2	$51.95	13.800%	$59.1191	$59.12	$59.10	$59.10
Purchase #3	$83.96	6.687%	$89.5744	$89.57	$89.55	$89.60
Purchase #4	$143.80	6.412%	$153.0205	$153.02	$153.00	$153.00
Purchase #5	$42.75	8.574%	$46.4154	$46.42	$46.40	$46.40
Purchase #6	$93.26	12.840%	$105.2346	$105.23	$105.25	$105.20
Purchase #7	$39.51	13.403%	$44.8055	$44.81	$44.80	$44.80
7 purchase totals =	$662.90		$725.5162	$725.52	$725.45	$725.40