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	$125.98	11.451%	$140.406	$140.41	$140.40	$140.40
Purchase #2	$59.64	11.249%	$66.3489	$66.35	$66.35	$66.30
Purchase #3	$17.54	11.310%	$19.5238	$19.52	$19.50	$19.50
Purchase #4	$240.81	3.172%	$248.4485	$248.45	$248.45	$248.40
Purchase #5	$146.38	4.416%	$152.8441	$152.84	$152.85	$152.80
Purchase #6	$202.85	9.549%	$222.2201	$222.22	$222.20	$222.20
Purchase #7	$244.98	3.423%	$253.3657	$253.37	$253.35	$253.40
7 purchase totals =	$1,038.18		$1,103.1571	$1,103.16	$1,103.10	$1,103.00