Many coin collectors store their valuable collection in these affordable holders(Whitman Tri-fold) . The problem that some of you have with this type of holder is that they do not always hold the coins in place.
Rather than placing tape across the face of the coins to hold them in place try this method.
Take the coin out of the slot. Take a 1/2" piece of tape and place part of it in the bottom of the slot, sticky side down and tuck it on to the side of the slot. This will take most of the slop out of that slot.Make sure you press the tape firmly into the side of the slot as this is were the slop needs to be taken out. Some times it may be necessary to do this to opposite sides of the coin slot. You may fine that masking tape will work better than Scotch tape.
By using this method your coins will stay put and you have the added benefit of not destroying them with the glue on the tape.