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	$176.61	11.444%	$196.8212	$196.82	$196.80	$196.80
Purchase #2	$61.66	12.141%	$69.1461	$69.15	$69.15	$69.10
Purchase #3	$241.30	11.550%	$269.1702	$269.17	$269.15	$269.20
Purchase #4	$102.48	11.659%	$114.4281	$114.43	$114.45	$114.40
Purchase #5	$152.67	13.706%	$173.595	$173.60	$173.60	$173.60
Purchase #6	$155.53	12.795%	$175.4301	$175.43	$175.45	$175.40
Purchase #7	$160.50	11.827%	$179.4823	$179.48	$179.50	$179.50
7 purchase totals =	$1,050.75		$1,178.0730	$1,178.08	$1,178.10	$1,178.00