Kevin,
What do you mean when you say: The Tax Collector endeavors not to misuse his power as a tax collector but nevertheless goes back home to his position of colluding with the enemy, he is still entangled in the sinful situation of collusion with the enemy but a journey of reconciliation has commenced?

This does not sound like Jesus' grace being poured out to a repentant sinner. Jesus' grace would never inspire our colluding with the enemy, but rather becoming obedient to His Will!  We want to please God, not continue in our sin. Yes, we will continue being a sinner, but not committing this sin. We will always struggle with our sinful natures throughout our entire lives and therefore will always need God's mercy, forgiveness and graces to become Saints (our spiritual goal in this life) and serve God!