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	$34.41	9.472%	$37.6693	$37.67	$37.65	$37.70
Purchase #2	$144.49	13.798%	$164.4267	$164.43	$164.45	$164.40
Purchase #3	$116.61	13.649%	$132.5261	$132.53	$132.55	$132.50
Purchase #4	$205.86	7.522%	$221.3448	$221.34	$221.35	$221.30
Purchase #5	$131.67	9.133%	$143.6954	$143.70	$143.70	$143.70
Purchase #6	$207.91	8.451%	$225.4805	$225.48	$225.50	$225.50
Purchase #7	$118.52	12.564%	$133.4109	$133.41	$133.40	$133.40
7 purchase totals =	$959.47		$1,058.5537	$1,058.56	$1,058.60	$1,058.50