I am a florist- if you say $50 that usually does not include the tax, which here would make your total $54.75....I always disclose if and how much any delivery charge is and state "the total, including tax and delivery charge, will be $xx.xx" that way the customer has the EXACT amount and if that goes over budget for them then they can say so.
If you want to spend $50 TOTAL then make sure to say TOTAL and then the florist (if they are a good one and accomodating) can back the tax and/or delivery charge out of that amount.
I have a customer who HATES the thought of paying tax to the gov't. So he places orders and says "I want to spend $40, no tax!" Well, I understand him so I say yes, sir and take good care of his order...BUT Uncle Sam still wants to get his tax so what the man gets in reality is a $32 floral arrg. and then the $4 delivery charge and then the tax makes up the remainder of the $40 he pays.
We are 65+ years a family florist- people love that what we say is what they pay. Not a penny more- plus we work with any budget. $10 or $1000, no prob. Next time, just specify and get a final price quote. Your charge is probably a nominal delivery charge- less than $5.