Why did reverend sykes say, "nobody leaves here till we have ten dollars? what does this tell us about the black community?

It was because the Robinsons had nowhere else to turn to expect the only people in the church which they consider as family with Tom Robinson in Jail. It was practically impossible for Helen to get the $10 dollars that she needed. If everyone in church donates she would have the money. For the fact that Reverend Skyes knows the difficulty that Helen would face if he allowed the congregation to leave with raising the money, he asked for the doors to be shut. Afterall, the bible commanded that we should love our neighbor as ourselves