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	$136.66	9.769%	$150.0103	$150.01	$150.00	$150.00
Purchase #2	$208.90	4.163%	$217.5965	$217.60	$217.60	$217.60
Purchase #3	$211.78	3.716%	$219.6497	$219.65	$219.65	$219.60
Purchase #4	$74.26	8.160%	$80.3196	$80.32	$80.30	$80.30
Purchase #5	$76.81	7.571%	$82.6253	$82.63	$82.65	$82.60
Purchase #6	$63.34	6.188%	$67.2595	$67.26	$67.25	$67.30
Purchase #7	$186.58	5.473%	$196.7915	$196.79	$196.80	$196.80
7 purchase totals =	$958.33		$1,014.2524	$1,014.26	$1,014.25	$1,014.20