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	$214.58	4.764%	$224.8026	$224.80	$224.80	$224.80
Purchase #2	$202.38	9.818%	$222.2497	$222.25	$222.25	$222.20
Purchase #3	$54.67	13.524%	$62.0636	$62.06	$62.05	$62.10
Purchase #4	$7.95	4.559%	$8.3124	$8.31	$8.30	$8.30
Purchase #5	$196.52	12.754%	$221.5842	$221.58	$221.60	$221.60
Purchase #6	$94.69	6.233%	$100.592	$100.59	$100.60	$100.60
Purchase #7	$242.44	8.631%	$263.365	$263.37	$263.35	$263.40
7 purchase totals =	$1,013.23		$1,102.9695	$1,102.96	$1,102.95	$1,103.00