My Raleigh has 7 cogs on it now, making it a 14 speed, but it doesn't have as low as a gear from when it was a 10 speed. The cluster's cogs aren't as wide ranged, meaning the amount of difference between gears. The old one had a bigger cog for low. so, it depends on the number of teeth on each cog on the cluster. You can get clusters for about 20 bucks at your local bike shop. If you have yours to compare, that will work best, count the teeth on the 5 cogs. If you need more hill climbing ability, get one that has more teeth on the lower gear, and vice versa.
Since your shifters are friction, and not synced for 5 speeds, you have to feel for the gears. That's good, you can get a cluster with more cogs, giving you more choice of gearing, for hilly and city at the same time.