How to Upgrade PHP version 5.4 to 5.6 on CentOS/RHEL 6/7

For CentOS/RHEL 7:

# rpm -Uvh https://mirror.webtatic.com/yum/el7/epel-release.rpm
# rpm -Uvh https://mirror.webtatic.com/yum/el7/webtatic-release.rpm
For CentOS/RHEL 6:

# rpm -Uvh https://mirror.webtatic.com/yum/el6/latest.rpm
For CentOS/RHEL 5:

# rpm -Uvh http://mirror.webtatic.com/yum/el5/latest.rpm
After installing Webtatic yum repository, you have to remove the old version of php-common package. It will also delete it dependencies packages.
# yum remove php-common

yum install -y php56w php56w-opcache php56w-xml php56w-mcrypt php56w-gd php56w-devel php56w-mysql php56w-intl php56w-mbstring php56w-fpm php56w-common php56w-soap