That would be pronounced “thrup-ence” or a thrup-ny bit. The old coinage started with a farthing (10 made a penny), then a halfpenny (pronounced hape-ny, then a penny, then a thrupenny, then a sixpence (brides would put a sixpence in their shoe for luck on their wedding day), then a shilling (which was 12 pennies), then a 2 shilling piece, then a 2 shilling and sixpence piece, after that paper money (ten shillings, a pound, etc).
Sing a song of sixpence,
A pocket full of rye.
Four and twenty blackbirds,
Baked in a pie.
When the pie was opened,
The birds began to sing;
Wasn’t that a dainty dish,
To set before the king?
The king was in his counting house,
Counting out his money;
The queen was in the parlour,
Eating bread and honey.
The maid was in the garden,
Hanging out the clothes,
When down came a blackbird
And pecked off her nose
I’ve got sixpence
Jolly. jolly sixpence
I’ve got sixpence to last me all my life
I’ve got twopence to spend
And twopence to lend
And twopence to send home to my wife-poor wife