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	$178.80	8.856%	$194.6345	$194.63	$194.65	$194.60
Purchase #2	$13.84	13.873%	$15.76	$15.76	$15.75	$15.80
Purchase #3	$132.60	9.191%	$144.7873	$144.79	$144.80	$144.80
Purchase #4	$171.41	4.542%	$179.1954	$179.20	$179.20	$179.20
Purchase #5	$152.64	5.707%	$161.3512	$161.35	$161.35	$161.40
Purchase #6	$72.83	7.737%	$78.4649	$78.46	$78.45	$78.50
Purchase #7	$103.49	5.596%	$109.2813	$109.28	$109.30	$109.30
7 purchase totals =	$825.61		$883.4746	$883.47	$883.50	$883.60