-Make a rectangle.
-Convert it to a path. (I set the stroke width to 5 for a 380x250 pixel barcode and also set the cap to "square cap")
-Remove both the left and right sides so only the top and bottom are remaining.
-With the object selected, Go to Path -> Path Effects.
-Add Stitch Sub-Paths. (I had to reverse the bottom line of the square horizontally because the stitches were crossed)
-Change the amount of paths to 50 or whatever you want.
-Make the Start Spacing Variance AND End Spacing Variance values the same. (2.00)
-Add some numbers with white backgrounds on the bottom and you've got a barcode! You might also want to go to the document properties and change the background to white so it will export all nice.
**Example SVG HERE**
**Or HERE**
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Sorry if the instructions aren't detailed enough, I'm in a hurry to go somewhere right now.