The 2, 2.5 etc you are seeing are fine, latency is only increased or decreased by .5 increments so there is problem there. Also, when overclocking the RAM you increase or loosen to timings, in order to maintain stability.
DIMM voltage should be increased by .1 increments.
Intel C2D E6320 / AMD Athlon X2 3800+
Gigabyte 965P DS3 / DFI nF4 Ultra-D
2GB OCZ Gold PC2-6400 / 2GB OCZ Gold PC4000
eVGA 8800GTS 320MB / eVGA 6800GS 256MB
150GB Raptor / 74GB Raptor
2x500GB / 320GB
OCZ GameXStreme 850w / OCZ StealthXStream 600w