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	$59.37	5.431%	$62.5944	$62.59	$62.60	$62.60
Purchase #2	$19.79	5.852%	$20.9481	$20.95	$20.95	$20.90
Purchase #3	$131.30	8.712%	$142.7389	$142.74	$142.75	$142.70
Purchase #4	$157.51	11.819%	$176.1261	$176.13	$176.15	$176.10
Purchase #5	$200.44	12.476%	$225.4469	$225.45	$225.45	$225.40
Purchase #6	$69.92	3.695%	$72.5035	$72.50	$72.50	$72.50
Purchase #7	$55.37	13.407%	$62.7935	$62.79	$62.80	$62.80
7 purchase totals =	$693.70		$763.1514	$763.15	$763.20	$763.00