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	$176.69	11.380%	$196.7973	$196.80	$196.80	$196.80
Purchase #2	$63.54	3.587%	$65.8192	$65.82	$65.80	$65.80
Purchase #3	$199.86	7.137%	$214.124	$214.12	$214.10	$214.10
Purchase #4	$90.42	11.447%	$100.7704	$100.77	$100.75	$100.80
Purchase #5	$125.76	7.704%	$135.4486	$135.45	$135.45	$135.40
Purchase #6	$242.94	5.596%	$256.5349	$256.53	$256.55	$256.50
Purchase #7	$61.91	7.234%	$66.3886	$66.39	$66.40	$66.40
7 purchase totals =	$961.12		$1,035.8830	$1,035.88	$1,035.85	$1,035.80