No tiles have to be cut if 9 tiles are laid at each end and 21 are laid along each side. (There are other ways to lay whole tiles, for example, 7*23.) The number of tiles needed is 2(9+21)=60 tiles, however they are laid. The total area is 60 * 0.5^2 sq m = 15 sq m, costing 15*75=$1125. Total cost=22500+1125=$23,625.
If the tiles are to be cut for the corners there will be 8 tiles for the ends and 22 for the sides. One of the 8 tiles has to be cut diagonally and one of the 22 tiles has to be cut diagonally. This means a total of 4 cuts costing $34. 8 half-tiles are created and these are placed at the corners. There are still 60 tiles in all, costing $1125, but we have to add the cost of cutting=$1159, making the total cost $23,659.