yum install php56w php56w-opcache
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.centos.webair.com
 * epel: mirrors.coreix.net
 * extras: mirrors.centos.webair.com
 * updates: mirrors.centos.webair.com
 * webtatic: uk.repo.webtatic.com
Resolving Dependencies
--> Running transaction check
---> Package php56w.x86_64 0:5.6.8-1.w6 will be installed
--> Processing Dependency: php56w-common(x86-64) = 5.6.8-1.w6 for package: php56w-5.6.8-1.w6.x86_64
--> Processing Dependency: php56w-cli(x86-64) = 5.6.8-1.w6 for package: php56w-5.6.8-1.w6.x86_64
--> Processing Dependency: php56w-cli = 5.6.8-1.w6 for package: php56w-5.6.8-1.w6.x86_64
--> Processing Dependency: httpd-mmn = 20051115 for package: php56w-5.6.8-1.w6.x86_64
---> Package php56w-opcache.x86_64 0:5.6.8-1.w6 will be installed
--> Running transaction check
---> Package php56w.x86_64 0:5.6.8-1.w6 will be installed
--> Processing Dependency: httpd-mmn = 20051115 for package: php56w-5.6.8-1.w6.x86_64
---> Package php56w-cli.x86_64 0:5.6.8-1.w6 will be installed
---> Package php56w-common.x86_64 0:5.6.8-1.w6 will be installed
--> Processing Dependency: libgmp.so.3()(64bit) for package: php56w-common-5.6.8-1.w6.x86_64
--> Finished Dependency Resolution
Error: Package: php56w-5.6.8-1.w6.x86_64 (webtatic)
           Requires: httpd-mmn = 20051115
           Installed: httpd-2.4.6-31.el7.centos.x86_64 (@base)
               httpd-mmn = 20120211
               httpd-mmn = 20120211x8664
               httpd-mmn = 20120211-x86-64
Error: Package: php56w-common-5.6.8-1.w6.x86_64 (webtatic)
           Requires: libgmp.so.3()(64bit)
 You could try using --skip-broken to work around the problem
 You could try running: rpm -Va --nofiles --nodigest