[bug]: Lose numeric zeros when rounding in duckdb

### Description

```sql
create table t(a numeric);
insert into t values (1.8000), (1.346);
select round(a, 2) from t;
```

With PG execution this returns:
```
 round
───────
  1.80
  1.35
```

With DuckDB execution this returns:
```
 round
───────
   1.8
  1.35
```

So we somehow lose the trailing 0 after rounding to two decimals. This causes differences in TPCDS output.