We use Ink to make electronic part svg's for an electronic circuit program called Fritzing, and when I make the production Gerber file - Gerber drill file controls a CNC drilling machine using X,Y coordinates -, the holes are a touch out.

Looking at the Gerber it looks like my gold circles "snap center of objects" to the grid correctly, because the same coordinate error is in both rows of holes, making it look like the actual setting of the grid in Document Properties doesn't translate to the drawing perfectly.

I set a grid up and snap the circles to it.

My ECU plug svg


Gerber drill hole locations in inch.
Notice the same Y locations for both X coordinate groups, indicating the "snap center of objects" to grid was perfect -.
X009722Y003865
X009722Y005244
X009722Y006620
X009722Y007840
X009722Y009019
X009722Y010203
X009722Y011386
X009722Y012565
X009722Y013744
X009722Y014928
X009722Y016111
X009722Y017328
X009722Y018711
X009722Y021152
X009722Y022369
X009722Y023552
X009722Y024732
X009722Y025911
X009722Y027094
X009722Y028277
X009722Y029456
X009722Y030636
X009722Y031861
X009722Y033235

X011492Y003865
X011492Y005244
X011492Y006620
X011492Y007840
X011492Y009019
X011492Y010203
X011492Y011386
X011492Y012565
X011492Y013744
X011492Y014928
X011492Y016111
X011492Y017328
X011492Y018711
X011492Y021152
X011492Y022369
X011492Y023552
X011492Y024732
X011492Y025911
X011492Y027094
X011492Y028277
X011492Y029456
X011492Y030636
X011492Y031861
X011492Y033235

This is actual Gerber dimensions Vs what was set in the grid of Document Properties.
This indicates some sort of error between the set grid and what gets put on the drawing for objects to snap to.
3.50266 3.50000
3.49504 3.50000
3.09880 3.10000
2.99466 3.00000
3.00736 3.00000
3.00482 3.00000
2.99466 3.00000
2.99466 3.00000
3.00736 3.00000
3.00482 3.00000
3.09118 3.10000
3.51282 3.50000
6.20014 6.20000
3.09118 3.10000
3.00482 3.00000
2.99720 3.00000
2.99466 3.00000
3.00482 3.00000
3.00482 3.00000
2.99466 3.00000
2.99720 3.00000
3.11150 3.10000
3.48996 3.50000

If I click on the nodes in INK and subtract their location coordinates, it also shows that slight error.

Maybe setting precision to a higher value in the preferences could help? There are two values, in Edit -> Preferences -> Input/Output -> SVG Output.

Quote from the manual:
"numericalprecision

Default: 8. This is the number of significant digits written out for a number. Lowering the number will save a small amount of space at a cost of precision.

minimumexponent

Default: -8. Any number smaller than 10 raised to this value (10-8) is written out as 0."

Disclaimer: didn't try, just an idea for you to test

Don't know the exact core of the problem, but in 0.92 there is another option in the document's properties to set the scale of user units. Maybe if it's set to 1 and all transformations are eliminated (resizing page?) the rounding error will be less.

It must be something in the original svg - it was some conversion from another program thing -, because when I snap 5 circles to a grid on a new drawing in inch and mm, it's perfect.

I think I am going to redraw the whole thing again on a new sheet to get rid of any XML group attribute thing, that I'm not smart enough to understand and edit out. I notice the child nodes in parent groups go haywire and fly all over the place when you move them out of a group, if I start from scratch it will remove all that stuff.

It was out about 6 - 1000 of a mm ADV, now it's 6 - 10,000 of a mm.

Gerber - Actual - ABS Difference
3.50012 3.50000 0.00012
3.50012 3.50000 0.00012
3.09880 3.10000 0.00120
2.99974 3.00000 0.00026
3.00228 3.00000 0.00228
2.99974 3.00000 0.00026
2.99974 3.00000 0.00026
2.99974 3.00000 0.00026
3.00228 3.00000 0.00228
2.99720 3.00000 0.00280
3.10134 3.10000 0.00134
3.50012 3.50000 0.00012
6.20014 6.20000 0.00014
3.09880 3.10000 0.00120
2.99974 3.00000 0.00026
2.99974 3.00000 0.00026
3.00228 3.00000 0.00228
2.99974 3.00000 0.00026
2.99974 3.00000 0.00026
2.99974 3.00000 0.00026
2.99974 3.00000 0.00026
3.09880 3.10000 0.00120
3.50012 3.50000 0.00012

The node coordinates are perfect in INK now, so I assume it must be the conversion in the Gerber from inch to mm.

Old drawing had mysterious XML somewhere, so the problem is solved by making a new one.