We have about 20 Masjids in our area. Each Masjid asked for a different amount of money for Zakatul-Fitr; e.g., one asked 3 dollars, another 5 dollars, another 7 dollars, and one 10 dollars.
1) If I pray in 2 Masjids, each with a different amount of Zakatul-Fitr, how much should I pay?
2) Is the person who decides the value of the Zakat in each Masjid considered sinful since he did not follow the order of Allah? I thought the value of the Zakat should be a fixed amount in one local area, isn’t it?
3) In general, how much Zakat should I pay every year?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

No doubt that the reference for giving the Zakatul-Fitr is the Sunnah of the Prophet . Muslim narrated that Ibn ‘Umar said: "Allah's Messenger prescribed the Zakatul-Fitr of Ramadan a Saa' (2480grams) of dates or one Saa' of barley for every individual among Muslims, free person or slave, male or female, young or old."

It is then given as clarified above from what the people of that country or state eat the most. Some scholars have made it lawful to give the value of this Zakat in currency.

This view is logical above all in countries like the USA and others. This value can differ from one place to another depending on the wealth of people and their purchasing power, and depending on the kind of food it is given from. The value of dates can be for instance 3 and the one of raisin 10 and so on. So you have the choice as long as you are choosing one of the alternatives available in your country. However, it is better for you to take the opinion of a religious and pious person.

Allah knows best.