I can answer for tanks.
Support tanks usually run Flat HP Quints. Armor red and yellows and scaling MR blues. The MR is not needed that much early game since who is going to be doing the damage is the enemy adc which primary is ad damage.
Scaling HP Seals can be used on tanks support but.... Usually flat Armor works better. So in reality spending on HP seals (flat or scaling) is not recommended. If you really need the extra HP I woudl go for the flat HP quint and Armor seals, if you already bought them thou you can interchange the, using Armor quint and flat HP seals. Ideally you want out of the 4 types of runes, 2 to be armor, 1 to be flat HP and 1 to be MR. Scaling HP seals are severely underpowered at the moment and I wouldn't recommend it.
Scaling armor seals are mostly used on mid laners which are against another mage (or ap champion) which would do magic damage. Again early game you don't need that much armor unless you are melee and will be forced to take a lot of minion aggro.
Tanks in the jungle do better running a standard mage or ad bruiser runes or even standard adc runes with a tank mastery set. They need some form of damage to speed up the clear times. I believe currently even Rammus prefers Attack Speed Runes over the full armor ones.
As for the scaling or flat CDR, I have never used anything other than flat CDR to achieve 5% CDR (the rest are either MR or mana regen) and then you woudl get Ionian boots (15%) so you only woudl need one item to get the cap. But since the nerf to ionian boots I have seen players take a mix of scaling and flat CDR to make up the 5% missing from the ionian. Personally I don't mind sitting on 35% so I still take my MR runes mix but is a mtter of preference.