A lot of thoughts, yes (ha), but the short version is:
- we're not under the Mosaic covenant so there's not a 1:1 between those specific laws and ours
- however, the general principle of giving, of 'the workman being worthy of his wages' obtains
- the NT encourages: a) giving; b) voluntarily; c) generously; d) cheerfully; e) regularly; even f) sacrificially (yet not irresponsibly)
Whether 'increase' is revenue or profit is debated; whether 10% is the ceiling or the floor, the idea is that we should be intentional and settled in our conscience about whatever amount we give. The purpose is gratitude, not merit; the use is for the expansion of the gospel and the (judicious) assistance of those in need amongst us (to all men, but especially the flock).
When we think about what the tithe represents it's rather insidious that the State 'takes' our firstfruits without our consent--but this is a side conversation and gets into our political philosophy.