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	$103.95	10.182%	$114.5342	$114.53	$114.55	$114.50
Purchase #2	$13.99	13.562%	$15.8873	$15.89	$15.90	$15.90
Purchase #3	$43.47	5.438%	$45.8339	$45.83	$45.85	$45.80
Purchase #4	$24.27	6.658%	$25.8859	$25.89	$25.90	$25.90
Purchase #5	$189.43	9.111%	$206.689	$206.69	$206.70	$206.70
Purchase #6	$51.99	5.596%	$54.8994	$54.90	$54.90	$54.90
Purchase #7	$54.28	6.503%	$57.8098	$57.81	$57.80	$57.80
7 purchase totals =	$481.38		$521.5395	$521.54	$521.60	$521.50