Include Tax in delivery time slot

Hello, i have a request, it is possible to include tax in price with delivery time slot. I explain with an exemple : There is an option for activate and disactive tax for time slot, it’s good, i make 15€ for specific time slot, if i don’t active tax, in delivera time slot list it’s (+15 €) and in the total it’s 15€ fee it’s ok. If i active tax, if i make 15€ delivers time slot, in the total it’s 15,37€, for have 15€ fee total with tax i must make 14.63€ on fees but on the list timeslot, it’s 09:00 – 10:00 (14.63 €). My question is it is possible to include tax for have visual 15€ in list and 15€ include tax in total. Many Thanks. (PS : Sorry for my bad english)