Fix nPayFee calculation

[Gabrola]

nPayFee is more than intended if nBytes is exactly in multiples of 1000
bytes

[ghost]

Would changing this to /1023 instead of /1000 result in faster code as the compiler could reduce this to a series of bit shifting operations?

[luke-jr]

@Gabrola What makes you think it's more than intended?

@NanoAkron It'd need to be /1024

[Gabrola]

@NanoAkron If you meant 1024, that still wouldn't work on really large transactions since the rule is 1,000 bytes not 1kB
@luke-jr nPayFee would be nTransactionFee * 2 if nBytes was 1000 when it should be just nTransactionFee * 1

[luke-jr]

@Gabrola My question is why you think it should be * 1.

[Gabrola]

The transaction relay rule states:
Base fee is: 10,000 satoshis per 1,000 bytes, transaction size rounded UP to the nearest 1,000 bytes (e.g. a 1,001 byte transaction requires a 20,000 satoshi fee). Can be changed with the -minrelaytxfee setting.

I don't think this implies that 1,000 bytes should round up to a 20,000 satoshi fee as well.

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[laanwj]

Is this consistent with the transaction selection in the mining code?

[Gabrola]

I just checked and it's not consistent with GetMinFee()
This means we'll need to change GetMinFee() first but that means we'll have to wait for the majority of miners to be using 0.9.99 before we change the client code.
Should we change GetMinFee() for now or just ignore the problem considering the unlikeliness of transaction sizes being exactly divisible by 1000?

[laanwj]

That's not worth it IMO. The fees system is being reworked any way with floating fees.

As long as GetMinFee and the wallet are consistent, it's fine at it is.

Thanks for checking.