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	$117.69	8.259%	$127.41	$127.41	$127.40	$127.40
Purchase #2	$66.28	6.765%	$70.7638	$70.76	$70.75	$70.80
Purchase #3	$215.57	5.605%	$227.6527	$227.65	$227.65	$227.70
Purchase #4	$102.88	13.719%	$116.9941	$116.99	$117.00	$117.00
Purchase #5	$197.30	13.660%	$224.2512	$224.25	$224.25	$224.30
Purchase #6	$60.67	11.380%	$67.5742	$67.57	$67.55	$67.60
Purchase #7	$172.71	5.529%	$182.2591	$182.26	$182.25	$182.30
7 purchase totals =	$933.10		$1,016.9051	$1,016.89	$1,016.85	$1,017.10