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	$234.32	11.404%	$261.0419	$261.04	$261.05	$261.00
Purchase #2	$11.53	3.141%	$11.8922	$11.89	$11.90	$11.90
Purchase #3	$87.52	3.371%	$90.4703	$90.47	$90.45	$90.50
Purchase #4	$194.59	6.171%	$206.5981	$206.60	$206.60	$206.60
Purchase #5	$140.80	4.854%	$147.6344	$147.63	$147.65	$147.60
Purchase #6	$215.61	8.448%	$233.8247	$233.82	$233.80	$233.80
Purchase #7	$61.51	6.282%	$65.3741	$65.37	$65.35	$65.40
7 purchase totals =	$945.88		$1,016.8357	$1,016.82	$1,016.80	$1,016.80