over hedge or under hedge in foreign exchange

in lammer plc jun 06 adapted, the exercise price of 1.88, the contract was 19.57 so i have rounded up to 20 contracts for calculation.

therefore it resulted into overhedge and got 621520(calculation is below) which was different from the answer by 859 (621520-620661)

so if the decimal is more or equal to 0.5 can i round up as usual ?? and calculate as overhedge like below ?

(the calculation below)

total amount = 20 x 31250 = £625000
premium payable = 0.0296 x 20 x 31250 = US18500
premium payable using spot = 18500/1.9156 = £9657

amount overhedged = 1150 000 – ( 20 x 31250 x 1.88) = 25000 and 25000/1.903 = £13137

total amount payable = 625000+9657-13137 = £621520