Battery Charging Using Battery University Information:
RC is how many minutes the battery will last at 25A discharge. Divide by 60 to get discharge time in hours, then multiply by 25 to get the effective capacity. Taking into account that capacity is reduced at high discharge rates, the nominal capacity of an 'RC110' battery is about 60Ah.
Charge current should be kept below 0.2C ('5 hour' rate) but 0.1C is better for the battery. At higher current the battery reaches peak voltage sooner but still takes the same time to top off, so there isn't much advantage in using a higher rate. 60Ah x 0.1C = 6A.
You want to go as high as you can without gassing, but the critical voltage is temperature dependent. If you can't measure the internal battery temperature accurately and provide the correct compensation then charge at room temperature and stay below 2.35V/cell (14V).
3% to 5% of the AH rating means just what it says. However 3% of 60Ah is 1.8A, which is quite high. A good battery should go much lower than this provided that it isn't gassing. The best way to ensure that the battery gets a full charge is to wait until the current stops dropping.


The 'topping' charge usually takes considerably longer than the initial 'bulk' charge, and must not be cut short if you want the battery to last. 


The 'correct' float voltage is 2.25-2.27V/cell (13.5-13.6V) at room temperature, but anywhere between 2.2V and 2.3V (13.2-13.8V) should be OK.