tall money meaning in English

大笔的财富
大宗财富

When buying authority certificate recently , clinch a deal finally the price that valence inputs than me unexpectedly nearly 5 minutes taller money , have other measure excuse me of the oldest rate reduce the price difference when clinching a deal
最近一次买权证时，最终的成交价比我输入的价竟高了近5分钱，请问有没有别的办法最大程度的降低成交时的价差？