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	$112.85	3.484%	$116.7817	$116.78	$116.80	$116.80
Purchase #2	$189.62	3.758%	$196.7459	$196.75	$196.75	$196.70
Purchase #3	$129.37	7.359%	$138.8903	$138.89	$138.90	$138.90
Purchase #4	$168.96	6.683%	$180.2516	$180.25	$180.25	$180.30
Purchase #5	$107.78	5.755%	$113.9827	$113.98	$114.00	$114.00
Purchase #6	$116.39	4.729%	$121.8941	$121.89	$121.90	$121.90
Purchase #7	$218.32	3.793%	$226.6009	$226.60	$226.60	$226.60
7 purchase totals =	$1,043.29		$1,095.1472	$1,095.14	$1,095.20	$1,095.20