I want to convert for below sample values

1. Rounding to the 4th digit (first 3 digits should be 0). No decimals. E.g.: 89231.1 should be 89000
2. Rounding to the 2th digit (first digit should be 0). No decimals. E.g.: 89.6 should be 90
3. Rounding to the 1st digit. No decimals. E.g. 75.6 should be 76