vagrant-cachier-ng/docs/buckets/yum.md

Yum

Used by CentOS guests, will get configured under guest's /var/cache/yum. It will also make sure that keepcache is set to 1 on guest's /etc/yum.conf.

To manually enable it:

Vagrant.configure("2") do |config|
  config.vm.box = 'some-centos-box'
  config.cache.enable :yum
end