Is your toilet running periodically 4 or 5 times a day and then stopping? It could be as simple as replacing a worn out flapper that is not sealing properly. It’s easy and inexpensive. If this does not solve the problem, you may want to check the toilet fill valve for wear and possible broken parts as well. Some parts are easy to replace yourself and if all fails call a licensed plumber. Start saving money on your water bill now. Chlorinated water will break down and wear out your toilet flapper faster than normal.
Taking the old flapper with you when you purchase a new one will help you purchase a matching replacement. The rubber flapper cap is the most common. It fits many toilet systems and is easily replaceable.