To round down is to lower a number to the nearest convenient one. Round down to the nearest hundred, always round down.
It is the pair to round up, and which you use depends on whether you would rather be under or over. Some charges must round down in the customer's favour by law.
1phraseround downTo lower a number to the nearest convenient one.
“Round down to the nearest pound and the total is fifty.”
round down is a phrase.
Practised in Numbers & Measurement