What rounding cannot do
A desk about a small mechanism should be as clear about its limits as about its findings. This page lists six things the rounding cannot do, each of them a consequence of the arithmetic rather than a reassurance.
- limits
- 6
- tail returned
- 0.00
- largest dust
- 0.00499999
- direction
- by rule
A rounding cannot return the fraction it withholds, and it cannot be seen on the number a balance displays. It cannot be relied on to cancel out, it is not a fee, it cannot make a small amount cheap, and it cannot change the expected result of the product it sits inside. Each of those is arithmetic, not reassurance.
The six limits
It can give back the fraction
No. The fraction withheld from a stake is stake that was never placed, so there is nothing to return: on sample B the 0.24 of tail across seven requests stayed in the account as unplaced money rather than arriving as a credit. A withheld return is the same: it was never paid, so it cannot be refunded.
falseIt can be seen on a balance
No, by construction. A fraction smaller than the display unit is exactly what the display cannot express, which is why 0.00499999 shows as 0.00 and why 99.9960 shows as 100.00. The information that would let a reader see it is the precision the interface chose to hide.
falseRounds up and rounds down cancel out
No. On sample G the duty was rounded up on every stake and the prize down on every prize, so the two directions reinforced rather than offsetting, and on sample D four accounts showed more than they held while three showed less. Cancellation requires the two directions to meet on the same event, which is not how a rules document is written.
falseIt is a fee
No. A fee is charged on a line and appears on a statement; a rounding leaves the fraction where it was and appears nowhere. Treating it as a fee overstates it - it never leaves the account - and treating it as nothing understates it, because 60.00 accumulated in sample H from the same turnover.
falseIt makes small amounts cheap
Partly. The opposite is true: because the cost of a rounding is fixed at one unit, it is a larger share of a small amount than of a large one, which is why the same conversion rule cost 1.75% of 0.50 and 0.00% of 100.00. What is true is that the absolute cost is small, so on a single event it is not worth arguing about.
partlyIt changes the expected result
True that it cannot, and it is worth stating plainly: no rounding in this desk makes a losing product profitable or a profitable one losing, because the fractions are far smaller than the margin any betting product is built on. A rounding decides who keeps the last decimal; it does not decide whether a player wins.
trueWhy this page exists
A mechanism this small is easy to present as either a scandal or a nothing, and both would be wrong. It is neither: it is a set of ordinary arithmetic decisions that a reader can find in the rules and can allow for with one round number. The page therefore ends where the desk began, with the same claim in the negative: the rounding decides which unit you get, never whether you win. Everything else on this site is about the first of those two facts.
- Keep the rounding in proportion: at most one unit per event, and a fraction of the price's own cost.
- Do not look for the fraction on a statement; it is deliberately below the display, not missing from it.
- Do not assume the directions cancel: read both the charge and the payment sides of a rules document.
- Judge a rounding rule as a rule, not as a fee or an error.
- Spend the attention on the price and the stake before spending it on the last decimal.