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	$39.68	10.726%	$43.9361	$43.94	$43.95	$43.90
Purchase #2	$21.78	11.636%	$24.3143	$24.31	$24.30	$24.30
Purchase #3	$71.83	3.768%	$74.5366	$74.54	$74.55	$74.50
Purchase #4	$77.40	5.371%	$81.5572	$81.56	$81.55	$81.60
Purchase #5	$189.95	13.109%	$214.8505	$214.85	$214.85	$214.90
Purchase #6	$75.29	4.382%	$78.5892	$78.59	$78.60	$78.60
Purchase #7	$211.56	8.323%	$229.1681	$229.17	$229.15	$229.20
7 purchase totals =	$687.49		$746.9520	$746.96	$746.95	$747.00