round a select, to more decimal values
Have a look at MS Docs about POWER function:


  Return Types
  Returns the same type as submitted in float_expression. For example, if a decimal(2,0) is submitted as float_expression, the result returned is decimal(2,0).  


CAST left operand as DECIMAL(18, NumDecimals)




-- without CAST

SELECT POWER(1 + (52/100.0) * 0.23, 0.268);
GO



| (No column name) |
| :--------------- |
| 1.03073935       |






-- CAST as DECIMAL(18,12)

SELECT POWER(CAST(1 + (52/100.0) * 0.23 AS DECIMAL(18,12)), 0.268);
GO



| (No column name) |
| :--------------- |
| 1.030739345889   |



dbfiddle here