How to round a floating point to nearest 10?

[Mensanator]

On Aug 9, 4:54 pm, John Machin <sjmac... at lexicon.net> wrote:
> On Aug 10, 1:19 am, Mensanator <mensana... at aol.com> wrote:
>
> > On Aug 9, 6:31 am, Will Rocisky <geekm... at gmail.com> wrote:
>
> > > I want my 76.1 to be rounded to decimal 80 and 74.9 to decimal 70.
> > > How can I achieve that?
> > >>> print '%.0e' % 74.9
> > 7e+01
> > >>> print '%.0e' % 76.1
>
> > 8e+01
>
> But:>>> print '%.0e' % 176.1
>
> 2e+002

Which would be correct if your goal was to restrain to
1 significant digit.

>
> Giving the Subject ("How to round a floating point to nearest 10?"),
> there's a strong presumption that the OP would want the answer to be
> 180, not 200.

Well, I can't read the OP's mind and the cases I HAVE encountered
are concerned about the number of significant digits. When
laboratories
report 3 digits, all my manipulations (ppm conversion, dividing
non-detect reporting limits by 2, comparison to TACO, etc. are
required to also have exactly 3 digits of significance).

>>> print '%.2e' % 0.00000123456
1.23e-006
>>> print '%.2e' % 123456
1.23e+005
>>> print '%.2e' % 0.123000456
1.23e-001

It all depends on what the OP actually wants. He's free to ignore
my example.