Grouping Eliminating Duplicates

Ok...this works

Marketing Count Test = 
    VAR 
        LoginTransactions =
            GROUPBY(
                ADDCOLUMNS(
                    IdentityLog,
                    "ModifiedTime",
                    TIME(
                        HOUR(IdentityLog[CreatedTime]),
                        MINUTE(IdentityLog[CreatedTime]),
                        0
                    )
                ),
                IdentityLog[IdentityId],
                IdentityLog[MarketingSourceLogId],
                IdentityLog[CreatedDate],
                [ModifiedTime]
            )
    VAR
        UniqueLogins =
            SUMMARIZE(
                LoginTransactions,
                IdentityLog[IdentityId],
                IdentityLog[CreatedDate],
                [ModifiedTime],
                "MarketingSource",
                MAX(IdentityLog[MarketingSourceLogId])
            )
    RETURN

    UniqueLogins

But this seems overly complicated.  I could achieve the same result with SUMMARIZECOLUMNS if I could truncate seconds from the time.  Could anyone please offer some guidance on how to achieve that?

This is what I was looking for!

Active Users by Marketing Source Earliest Attribution = 
    VAR 
        LoginTransactions =
            ADDCOLUMNS(
                SUMMARIZECOLUMNS(
                    IdentityLog[IdentityId],
                    IdentityLog[CreatedDate],
                    "Created Time",
                    MIN(IdentityLog[CreatedTime])
                ),
                "MarketingSource",
                LOOKUPVALUE(
                    IdentityLog[MarketingSourceLogId],
                    IdentityLog[IdentityId],
                    IdentityLog[IdentityId],
                    IdentityLog[CreatedDate],
                    IdentityLog[CreatedDate],
                    IdentityLog[CreatedTime],
                    [Created Time]
                )
            )
    RETURN

    COUNTROWS(LoginTransactions)