DecimalFormat automatically rounds output to the displayed number of decimal places, so there is nothing to do if you are rounding simply to make output look pretty.
Integer Division  Rounding Gotcha 
Round  Rounding to a Multiple 
Ceiling  Rounding Currency 
Floor  Rounding to a Nickel 
Truncate  Links 
Cover 
// integer division // What percentage is "after" of "before" expressed as number 0..100 percent int percent = ( after * 100 ) / before; // truncated down int percent = ( after * 100 + before  1) / before; // rounded up int percent = ( after * 100 + before/2) / before; // rounded
long Math.round( double ); int Math.round( float ); double Math.rint( double ); // rounding to two decimal places double roundedValue = Math.rint( value * 100.0d ) / 100.0d;
value  round 

1.6  2 
1.5  2 
1.4  1 
+1.4  +1 
+1.5  +2 
+1.6  +2 
double Math.ceil( double );See the description of covered quotient division.
value  ceil 

1.6  1 
1.5  1 
1.4  1 
+1.4  +2 
+1.5  +2 
+1.6  +2 
double Math.floor( double );See floored division.
value  floor 

1.6  2 
1.5  2 
1.4  2 
+1.4  +1 
+1.5  +1 
+1.6  +1 
int i = (int)d;
value  truncate 

1.6  1 
1.5  1 
1.4  1 
+1.4  +1 
+1.5  +1 
+1.6  +1 
d < 0 ? Math.floor( d ) : Math.ceil( d );
value  cover 

1.6  2 
1.5  2 
1.4  2 
+1.4  +2 
+1.5  +2 
+1.6  +2 
// rounding m up to next highest multiple of n int ceil = ( m + n  1 ) / n * n; // rounding m down to multiple of n int floor = m / n * n; // rounding m to nearest multiple of n int near = ( m + n/2 ) / n * n;
On 20130204 Canada discontinued the penny. Transactions are still computed to the penny, but are rounded to the nickel. The government has suggested (but not mandated) the following rounding rules.
The formula to compute the rounded amount could be described in words as.
You can calculate the rounded amount in a spreadsheet with =ROUNDDOWN((A1+2)/5)*5
The Canadian Sales Tax Calculator will compute the final sale amount including sales tax both penny and nickelrounded.
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