The odds of rolling 5 dice the same depends on the type of dice being rolled. For a 6-sided die, the odds of rolling all 5 dice with the same number is 1 in 6^4 or approximately 1 in 1296. This is because there are 6 possible outcomes for each roll, and there are 5 rolls, which means that are 6^5 possible outcomes overall.
More precisely, only 1 out of these 6^5 outcomes will result in all 5 dice showing the same number