16) 99.99 rounded to 0.1 is 100
17) 5 rounded to 1 is 5
18) 11.99 rouded to 1 is 12
19) 499 rouded to 100 is 500
20) 999 rouded to 1k is 1000
Remember, when rounding to the nearest x, if the parts smaller than x is greater or equal to x/2, round up. Otherwise, round down.
Example: Round 1367 to the nearest 1000: the parts smaller than 1k is 367. 367 is less than half or 1k (500). Therefore, the answer is 1000