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	$59.57	10.686%	$65.9357	$65.94	$65.95	$65.90
Purchase #2	$139.38	6.583%	$148.5554	$148.56	$148.55	$148.60
Purchase #3	$198.56	3.272%	$205.0569	$205.06	$205.05	$205.10
Purchase #4	$33.99	10.267%	$37.4798	$37.48	$37.50	$37.50
Purchase #5	$205.81	9.562%	$225.4896	$225.49	$225.50	$225.50
Purchase #6	$62.84	10.786%	$69.6179	$69.62	$69.60	$69.60
Purchase #7	$249.90	5.115%	$262.6824	$262.68	$262.70	$262.70
7 purchase totals =	$950.05		$1,014.8177	$1,014.83	$1,014.85	$1,014.90