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	$74.67	10.719%	$82.6739	$82.67	$82.65	$82.70
Purchase #2	$81.42	10.754%	$90.1759	$90.18	$90.20	$90.20
Purchase #3	$55.75	11.175%	$61.9801	$61.98	$62.00	$62.00
Purchase #4	$145.73	4.547%	$152.3563	$152.36	$152.35	$152.40
Purchase #5	$57.96	9.434%	$63.4279	$63.43	$63.45	$63.40
Purchase #6	$103.99	7.645%	$111.94	$111.94	$111.95	$111.90
Purchase #7	$180.58	11.228%	$200.8555	$200.86	$200.85	$200.90
7 purchase totals =	$700.10		$763.4096	$763.42	$763.45	$763.50