Plenty of practice here at counting on in fives, right up to 100. As confidence grows children should recognise the patterns involved with counting in fives. The units digit is always a five or zero. They alternate, also making odd and even numbers.
Don’t mistake the ability to count up in fives with knowing the 5 times table. In this case it is the pattern which is important (later leading to rules of divisibility), but children should not need to count up in fives to work out 6 times 5.