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	$146.80	10.240%	$161.8323	$161.83	$161.85	$161.80
Purchase #2	$222.40	7.766%	$239.6716	$239.67	$239.65	$239.70
Purchase #3	$59.40	6.483%	$63.2509	$63.25	$63.25	$63.30
Purchase #4	$87.87	4.761%	$92.0535	$92.05	$92.05	$92.10
Purchase #5	$102.52	11.582%	$114.3939	$114.39	$114.40	$114.40
Purchase #6	$172.37	13.750%	$196.0709	$196.07	$196.05	$196.10
Purchase #7	$200.58	9.308%	$219.25	$219.25	$219.25	$219.30
7 purchase totals =	$991.94		$1,086.5231	$1,086.51	$1,086.50	$1,086.70