Urgent Help Needed with time formula converting 100s to 60S

Hi

I'm creating a calculator which I have attached.

Basically I need to convert times in 100 minute clock E.G 1.75 which need to be changed to 1.45, That then needs to be rounded up to the nearest 10mins so 1.75 will need to change to 1.45 and then rounded up to 1.5, It always need rounding up even if its 1.41. It then needs to be converted once it’s been rounded up back to the 100 minute clock, so 1.75 - 1.45 - 1.5 - 1.84

If anyone could help be greatly appreciated

Thanks