The rig bonus multiplier is 1.0 for highsec, 1.06 for lowsec and 1.12 for nullsec/wormhole
So: 54% highsec; 57.24% lowsec; 60.48% nullsec/wormhole.
There are separate rigs for highsec, low/null minerals and highsec, now/null ice so a 54% facility may not be 54% for what you are trying to reprocess.
The HS rig works for Kernite, Omber, Plagioclase, Pyroxeres, Scordite, Veldspar (and all their variants)
The LSN rig works for Arkonor, Bistot, Crokite, Dark Ochre, Gneiss, Hedbergite, Hemorphite, Jaspet, Mercoxit, Spodumain (and all their variants)
Same deal with Ice. I1 and I2 rig varients.
Edit: the variants are for medium structures (Astrahus, Raitaru) Rigs for large structures are divided ore and ice. XL rigs reprocess everything.