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	$200.47	10.873%	$222.2671	$222.27	$222.25	$222.30
Purchase #2	$62.78	7.526%	$67.5048	$67.50	$67.50	$67.50
Purchase #3	$91.74	4.395%	$95.772	$95.77	$95.75	$95.80
Purchase #4	$67.25	8.351%	$72.866	$72.87	$72.85	$72.90
Purchase #5	$207.33	8.666%	$225.2972	$225.30	$225.30	$225.30
Purchase #6	$186.61	11.682%	$208.4098	$208.41	$208.40	$208.40
Purchase #7	$60.39	4.761%	$63.2652	$63.27	$63.25	$63.30
7 purchase totals =	$876.57		$955.3821	$955.39	$955.30	$955.50