Actually, I don't know of any Christian denomination or individual that tithes according to the Torah of Moshe. Tithing (עישור) is a relatively complicated process in Judaism, and of course, it's hardly (if at all) practical without a Temple. If Jews cannot tithe without the Temple, then Christians certainly cannot.
With that being said, the general concept behind tithing is support of a ministry. As the Levites ministered in the Temple, and had no particular city or inheritance to lay claim to, they were thus supported by the other Israelites. Christians support the ministry of their pastors and particular churches which likewise serve God and His people.
To be specific, not a single soul tithes according to the Torah since the destruction of the Temple. Therefore, one does not need to look for a verse to support tithing, because the endeavor is futile.
On the other hand, if we're talking about the general idea of fiscal support for the ministers of God, then yes, there is a biblical basis for its current practice. Churches freely gave to Paulos in order to support his ministry (cp. 2 Cor. 11:8-9; 1 Cor. 9:6-18). One could not have expected Paulos to have a day-to-day occupation when he was traveling around the region preaching the gospel, could he?
Paulos wrote, "Even so, the Lord has ordained that those who preach the gospel should live of the gospel" (1 Cor. 9:14), and he declared that he had the authority to not work (1 Cor. 9:6).
(I doubt that I can, nor do I wish to, change the common understanding of "tithing," but for the sake of this discussion, I thought it was important to make such a distinction.)
Now, respecting the verses in question, as you quoted them:
Luke 11:42:
“But woe to you Pharisees! For you tithe mint and rue and every herb, and neglect justice and the love of God. These you ought to have done, without neglecting the others.” (ESV)
Matthew 23:23:
“Woe to you, scribes and Pharisees, hypocrites! For you tithe mint and dill and cumin, and have neglected the weightier matters of the law: justice and mercy and faithfulness. These you ought to have done, without neglecting the others.” (ESV)
You asked:
So, was Jesus implying that all his followers tithe? Or was he only speaking specifically to the Pharisee who was trying to live under the law?
Actually, the Prushim did not have a choice to obey the commandment to tithe and "live under the Law." They were living in the economy of the Old Covenant, under the παιδαγωγός of the Torah of Moshe, so they were obligated to tithe, for God explicitly commanded it.
Jesus' criticism of the Prushim concerns their "hypocrisy" --- focusing on mitzvot kalot ("light commandments") while neglecting the mitzvot chamurot ("heavy commandments") (cp. Matt. 5:19). They were most scrupulous in tithing and focusing on the mitzvot kalot, but they would pervert justice, lack faith, and be merciless towards the laity.
Another example of this hypocrisy is Matt. 15; Mark 7, where the Prushim admonish Jesus' disciples for eating with dirty hands. It wasn't actually prohibited to eat with dirt on one's hands, according to the written Torah. This was a rabbinic decree, later codified in the Mishna. While the Prushim would be scrupulous about immersing so-called "unclean hands" (yadayim meso'avot or yadayim mezochamot), they were unconcerned that "from within, out of the heart of men, proceed evil thoughts, adulteries, fornications, murders...all these evil things come from within, and defile the man" (Mark 7:23).
Paulos later wrote, "For they being ignorant of God's righteousness, and going about to establish their own righteousness, have not submitted themselves unto the righteousness of God" (Rom. 10:3).
Who does the pronoun "you" refer to??
One might assume that all Christians are being referred to, but I believe this to be erroneous exegesis. It is clear that Jesus, like those whom he was speaking to, was born "under the Law" (Gal. 4:4). It's hardly realistic for a Christian today to assume that Jesus implored us to tithe. 1) We're not born under the Law, and 2) we live in an economy of grace (Eph. 3:2). It's absolutely imperative that the relevance of the Torah of Moshe is considered. To the Prushim, it was absolutely relevant; to us, it is essentially irrelevant. Christians, whether Jew or Gentile, keep the Law of Christ (Gal. 6:2), not the Law of Moshe. Indeed, there is a saying in Midrash Kohelet Rabba that "the Law that man learned in this world is vanity in the presence of the Messiah's Law."
As the Old Covenant passed away, so did the Law of Moshe.