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	$152.98	7.665%	$164.7059	$164.71	$164.70	$164.70
Purchase #2	$152.77	13.643%	$173.6124	$173.61	$173.60	$173.60
Purchase #3	$33.73	3.216%	$34.8148	$34.81	$34.80	$34.80
Purchase #4	$13.49	4.219%	$14.0591	$14.06	$14.05	$14.10
Purchase #5	$196.62	6.222%	$208.8537	$208.85	$208.85	$208.90
Purchase #6	$164.93	8.693%	$179.2674	$179.27	$179.25	$179.30
Purchase #7	$9.30	13.152%	$10.5231	$10.52	$10.50	$10.50
7 purchase totals =	$723.82		$785.8364	$785.83	$785.75	$785.90