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	$59.56	3.622%	$61.7173	$61.72	$61.70	$61.70
Purchase #2	$9.40	6.866%	$10.0454	$10.05	$10.05	$10.00
Purchase #3	$63.47	10.190%	$69.9376	$69.94	$69.95	$69.90
Purchase #4	$72.81	13.824%	$82.8753	$82.88	$82.90	$82.90
Purchase #5	$29.38	12.428%	$33.0313	$33.03	$33.05	$33.00
Purchase #6	$104.72	4.612%	$109.5497	$109.55	$109.55	$109.50
Purchase #7	$185.47	10.301%	$204.5753	$204.58	$204.60	$204.60
7 purchase totals =	$524.81		$571.7319	$571.75	$571.80	$571.60