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	$168.42	7.271%	$180.6658	$180.67	$180.65	$180.70
Purchase #2	$223.33	7.361%	$239.7693	$239.77	$239.75	$239.80
Purchase #3	$183.72	4.217%	$191.4675	$191.47	$191.45	$191.50
Purchase #4	$46.35	5.549%	$48.922	$48.92	$48.90	$48.90
Purchase #5	$163.58	6.849%	$174.7836	$174.78	$174.80	$174.80
Purchase #6	$221.72	7.548%	$238.4554	$238.46	$238.45	$238.50
Purchase #7	$60.55	10.666%	$67.0083	$67.01	$67.00	$67.00
7 purchase totals =	$1,067.67		$1,141.0719	$1,141.08	$1,141.00	$1,141.20