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	$59.38	4.564%	$62.0901	$62.09	$62.10	$62.10
Purchase #2	$30.67	3.857%	$31.8529	$31.85	$31.85	$31.90
Purchase #3	$18.59	4.508%	$19.428	$19.43	$19.45	$19.40
Purchase #4	$28.54	3.212%	$29.4567	$29.46	$29.45	$29.50
Purchase #5	$204.82	9.569%	$224.4192	$224.42	$224.40	$224.40
Purchase #6	$135.78	4.592%	$142.015	$142.02	$142.00	$142.00
Purchase #7	$14.80	4.804%	$15.511	$15.51	$15.50	$15.50
7 purchase totals =	$492.58		$524.7729	$524.78	$524.75	$524.80