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	$87.26	9.871%	$95.8734	$95.87	$95.85	$95.90
Purchase #2	$133.50	11.182%	$148.428	$148.43	$148.45	$148.40
Purchase #3	$144.55	9.424%	$158.1724	$158.17	$158.15	$158.20
Purchase #4	$116.51	10.330%	$128.5455	$128.55	$128.55	$128.50
Purchase #5	$119.73	9.608%	$131.2337	$131.23	$131.25	$131.20
Purchase #6	$123.66	6.358%	$131.5223	$131.52	$131.50	$131.50
Purchase #7	$212.62	12.630%	$239.4739	$239.47	$239.45	$239.50
7 purchase totals =	$937.83		$1,033.2492	$1,033.24	$1,033.20	$1,033.20