Slabwise Withholding Tax

Dear Experts,

Withholding Tax on Contractors for Bangladesh is having slapwise, where I am using the formula based withholding calculation, but the output calculation is not correct as per the slab.

In formula i have use as under;

1,00,000 0

5,00,000 1%

15,00,000 2.5%

25,00,000 3.5%

99,99,999 4.0%

Below is the client requirement

The tax rate for supplier is always calculated on cumulative amount paid in a financial year. The rate is

Payment upto 1,00,000 Nil,

Payment exceed 1,00,000 but less than 5,00,000 is 1%

Payment exceed 5,00,000 but less than 15,00,000 is 2.5%

Payment exceed 15,00,000 but less than 25,00,000 is 3.5%

Payment exceed 25,00,000 is 4%

For Example,

1) If 1st payment is 25,000, the tax is nill.

2) If 2nd payment is 90,000, then tax is

Total payment (25,000+90,000)= 115000 @ 1% = 1150

3) If the 3rd payment is 500000, then tax is,

Total payment (25,00090,0005,00,000)= 6,15,000 @ 2.5%= 15375 u2013 1150 ( earlier tax deducted) = 14225

4) If the 4th payment is 1200000, then tax is

Total payment (25000900005000001200000)= 1815000 @ 3.5% = 63625- (115014225)= 48150

5) If the 5th payment is 700000, then tax is

Total payment (25000900005000001200000700000)= 2515000@4% = 100600- (11501422548150)= 37075

Please give your valuable suggestion for the withholding settings.

Thanks in advance

Sayed