score:2

Accepted answer

Change this line to return 7.01b as the max of the y axis

y.domain([0, d3.max(data, function(d) { return d["Tax Collections"]; })]);

y.domain([3000000000, 7000000001])

if you still want to use the function, how about

y.domain([ 
    d3.min( data, function(d){ return 1e9*Math.floor(d["Tax Collection"]/1e9); }, 
    d3.max( data, function(d){ return 1e9*Math.ceil(d["Tax Collection"]/1e9); }
]);

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