About Upgrading to +13

Hi I just want to know if i upgrade my item to +13 do u think there is a possible to failed? because the chances is

95% success so that means there is only a 5% chances to failed while upgrading, so it means every time I want to

upgrade my item to +10 to +13 I think there is no possibility to failed? just want to clear about upgrading items

because im afraid to lost some of my expensive item even if theres a free credits in voting .

Item +10 succes rate: 95%
Item +11 succes rate: 95%
Item +12 succes rate: 95%
Item +13 succes rate: 95%

sure there is 5% chances to fail when upgrading ... so you better buy it +13 from webshop