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	$209.77	11.258%	$233.3859	$233.39	$233.40	$233.40
Purchase #2	$97.50	11.236%	$108.4551	$108.46	$108.45	$108.50
Purchase #3	$198.61	5.538%	$209.609	$209.61	$209.60	$209.60
Purchase #4	$12.33	9.720%	$13.5285	$13.53	$13.55	$13.50
Purchase #5	$80.97	6.225%	$86.0104	$86.01	$86.00	$86.00
Purchase #6	$196.98	11.167%	$218.9768	$218.98	$219.00	$219.00
Purchase #7	$167.96	13.481%	$190.6027	$190.60	$190.60	$190.60
7 purchase totals =	$964.12		$1,060.5684	$1,060.58	$1,060.60	$1,060.60