PowerQuery Rounding Issues

The default rounding mode for power query is to handle the mid-point by rounding to the closest even number.

Since you seem to want to round away from zero, you need to replace Number.Round(number, [digits]) in your M-code with Number.Round(number, [digits], RoundingModeAwayFromZero).

Excel ROUND inherently does RoundAwayFromZero, and VBA.Round does RoundToEven

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMjRQitUBUoZ6RqYQlpEelGEMYsQCAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Main = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Main", type number}}),
    
    #"Added Custom" = Table.AddColumn(#"Changed Type", "PQ Round", 
        each Number.Round([Main ]), type number),
    
    #"Added Custom0" = Table.AddColumn(#"Added Custom", "RoundUp", 
        each Number.RoundUp([Main]), type number),
    
    #"Added Custom1" = Table.AddColumn(#"Added Custom0", "RoundDown", 
        each Number.RoundDown([Main]), type number),
    
    #"Added Custom2" = Table.AddColumn(#"Added Custom1", "RoundAwayFromZero 1", 
        each Number.Round([Main],0,RoundingMode.AwayFromZero), type number)

in
    #"Added Custom2"