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	$216.44	4.778%	$226.7815	$226.78	$226.80	$226.80
Purchase #2	$54.52	13.660%	$61.9674	$61.97	$61.95	$62.00
Purchase #3	$129.63	7.587%	$139.465	$139.47	$139.45	$139.50
Purchase #4	$145.61	3.575%	$150.8156	$150.82	$150.80	$150.80
Purchase #5	$193.52	4.305%	$201.851	$201.85	$201.85	$201.90
Purchase #6	$224.59	4.245%	$234.1238	$234.12	$234.10	$234.10
Purchase #7	$165.55	9.504%	$181.2839	$181.28	$181.30	$181.30
7 purchase totals =	$1,129.86		$1,196.2882	$1,196.29	$1,196.25	$1,196.40