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	$22.48	11.522%	$25.0701	$25.07	$25.05	$25.10
Purchase #2	$111.89	3.661%	$115.9863	$115.99	$116.00	$116.00
Purchase #3	$192.59	4.298%	$200.8675	$200.87	$200.85	$200.90
Purchase #4	$169.33	4.493%	$176.938	$176.94	$176.95	$176.90
Purchase #5	$146.36	10.693%	$162.0103	$162.01	$162.00	$162.00
Purchase #6	$77.27	10.484%	$85.371	$85.37	$85.35	$85.40
Purchase #7	$55.96	10.406%	$61.7832	$61.78	$61.80	$61.80
7 purchase totals =	$775.88		$828.0264	$828.03	$828.00	$828.10