How to say "totally it was a good day"?
Can I use 一共 for "totally"? For example: "一共我有了好天"?
Chinese will say “今天真不错！” or "今天真是太棒了！" Of course there are more idioms to express similar feelings.
Just FYI, when totally means in total, you can translate totally as 一共. However, when totally means completely, definitely, wholly, which is different from in total obviously, you cannot translate it into 一共. You can use 绝对，真地是，etc. In another scenario, when you use "totally" to show agreement on another person's opinions, for example, "This is a fantastic game.""Yeah! Totally!" , you can say "当然！"“绝对地！”“没错！”in Chinese.
I think your "totally" here means 总的 or 总的来说
I I didn't misread your original sentence means:
Altogether today was (actually) alright.
The front "今天，总的来说" just means "altogether today" (you can say 总的来说，今天 aswell). If you want the end to sound better than "还算可以" then you can change it to whatever you want.