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	$145.92	4.636%	$152.6849	$152.68	$152.70	$152.70
Purchase #2	$145.64	5.737%	$153.9954	$154.00	$154.00	$154.00
Purchase #3	$248.30	12.437%	$279.1811	$279.18	$279.20	$279.20
Purchase #4	$90.64	13.362%	$102.7513	$102.75	$102.75	$102.80
Purchase #5	$152.82	7.452%	$164.2081	$164.21	$164.20	$164.20
Purchase #6	$17.81	12.667%	$20.066	$20.07	$20.05	$20.10
Purchase #7	$184.59	6.450%	$196.4961	$196.50	$196.50	$196.50
7 purchase totals =	$985.72		$1,069.3829	$1,069.39	$1,069.40	$1,069.50