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	$181.84	8.219%	$196.7854	$196.79	$196.80	$196.80
Purchase #2	$241.35	3.117%	$248.8729	$248.87	$248.85	$248.90
Purchase #3	$116.39	12.715%	$131.189	$131.19	$131.20	$131.20
Purchase #4	$239.59	6.634%	$255.4844	$255.48	$255.50	$255.50
Purchase #5	$77.43	12.197%	$86.8741	$86.87	$86.85	$86.90
Purchase #6	$18.37	5.697%	$19.4165	$19.42	$19.40	$19.40
Purchase #7	$167.26	5.408%	$176.3054	$176.31	$176.30	$176.30
7 purchase totals =	$1,042.23		$1,114.9277	$1,114.93	$1,114.90	$1,115.00