Escrow is merely a special type of holding account. Are you referring to putting Earnest Money in escrow? Fund can be put in escrow for various reasons - earnest money, repair funds, taxes and insurance (lenders typically do that).
Earnest Money is usually somewhere between $1000 and 1% of price, but it can be more if you want to indicate high commitment to the selling agent. These funds are typically held in Escrow and applied to the purchase at closing.
You may need to define more clearly what you mean by escrow. In general "escrow" is an account which is meant to hold funds until a transaction is complete or something along those lines. For instance a property manager needs to have an escrow account set up to hold funds such as damage deposits, which are not theirs until a tenant leaves and the landlord proves they have damages which need to be paid for from that account. If you are referring to escrow in terms of buying a property, and you want to know what the title company is going to charge then you need to get the netsheet from them. Those costs will/may include flood certs, title insurance etc. Unless you are referring to something else entirely.