The term you're looking for is not 'raising' (poker)- but rather 'pressing'. A full press is to double your bet that a number will roll- for instance going from a $10 bet that a 9 rolls to a $20 bet. This is usually done using the 'payout'- money you get when that number has just rolled- thus betting an increased ammount of money that your number will roll a second time before a 7 is rolled. Instead of a full press however, a player may elect to press only one 'unit', which is a variable amount depending on your bet- but for the most part one unit is $5 when betting on the 4,5,9 or 10 - and $6 when betting on the 6 or 8.
Example: I bet a $10 nine
before the dealer pays me I say 'press to 20 please'
the dealer gives me $4 in change (a $10 nine pays $14)
now when the nine rolls again I want to increase my bet from $20 to $25 so I say:
'press one unit'