Improper rounding with PHP round() and a 14 decimal float -

i have age-old floating point rounding issue many people before me have, can't seem find solution situation. i'm doing math operations in mysql , returning result php float, using round() round result. problem i'm running numbers 10.50499999999977 seem trip round(), rounding number 10.5 instead of expected 10.51.

is there consistent way have php round number correctly? found quick solution, i'm afraid wouldn't hold in long run:

echo round(10.50499999999977, 2, php_round_half_up); // 10.5 echo round(round(10.50499999999977, 5, php_round_half_up), 2); // 10.51 

i'm worried if use solution , try round number 10.50444449 end rounding wrong (10.5 vs 10.51).

so there solution can use consistently correct rounded number php?

you're seeing expected behavior:

php>  echo round(10.50499999999977); 11 php > echo round(10.50499999999977, 1); 10.5 php > echo round(10.50499999999977, 2); 10.5 php > echo round(10.50499999999977, 3); 10.505 php > echo round(10.50499999999977, 4); 10.505 php > echo round(10.50499999999977, 6); 10.505 php > echo round(10.50499999999977, 7); 10.505 

as per docs:

php_round_half_up round val precision decimal places away zero, when half way there. making 1.5 2 , -1.5 -2.

...049999 isn't "half-way there". it's below 0.5, php rounds down.