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	$178.64	11.653%	$199.4569	$199.46	$199.45	$199.50
Purchase #2	$67.37	7.755%	$72.5945	$72.59	$72.60	$72.60
Purchase #3	$70.97	7.815%	$76.5163	$76.52	$76.50	$76.50
Purchase #4	$191.30	7.161%	$204.999	$205.00	$205.00	$205.00
Purchase #5	$10.42	9.827%	$11.444	$11.44	$11.45	$11.40
Purchase #6	$19.59	3.601%	$20.2954	$20.30	$20.30	$20.30
Purchase #7	$101.25	8.261%	$109.6143	$109.61	$109.60	$109.60
7 purchase totals =	$639.54		$694.9204	$694.92	$694.90	$694.90