How do round 260 milliliters to the nearest centimeter???

what you are really asking crosses over from measurement of volume to dosage per weight and there is no method to do that
the direction for dosing will say how many ml to use per pound of animal
so if it is 5ml per pound of animal , weigh the animal and multiply that by the 5ml and you will get your answer

To be exact 4.92892 just round up to 5

Here is a chart and calculator.
milliliters to teaspoons ml to tsp and tsp to ml teaspoons to milliliter...

Really? cc = ml. Therefore 0.5ml

One milliliter is 1/1000 of a liter or 1 cubic centimeter. One milliliter of water weights 1 gramme. So if you are speaking of water, one milligramme water equals 1/1000 milliliter.

41,004 milliliters is 41,004 cubic centimeters.

Zero centimeters, for anything less than half a centimeter.

There are ten milliliters in a centiliter, so 28.208 ml is 2.8208 cl.

10cm is 100mm (millimeters, not milliliters).

cm is centimeter, mm is millimeter. "centi" means one-hundredth, "milli" means one-thousandth.

A cc is a cubic centimeter, which is the same thing as ml (milliliter).

One imperial fluid ounce is 28.413075 cc.
One US fluid ounce is about 29.5735 cc.

The formula for this would be ¶r2h

So pi being 3.14 X 1.5 Inch X 12Inch = 56.52 Cubic inches

1 cubic inch = 16.387064 milliliters
Answer: 56.52 in³ = 926.196 ml