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I want to round off the amount in 5 cents. I tried that formula
amount = amount+0.05;
amount = amount *5;
amount = amount /5;
is this correct?

So let $A$ be the ammount. (Example: $23.27$)

Then $frac A{0.05} = frac {100A}5 = 20A$ is the number of $.05$ units the amount contains. (Example: $23.27$ has $465.4$ such units.)

Then we must round $20A$ to the nearest unit. So $round(20A)$ is the closest number of units (Example: $465$.)

Then you multiply but $0.05$ to get $0.05(round(20A))$ the nearest amount (Example $0.05(round(20*23.27))=0.05(round(465.4)) = 0.05times 465 = 23.25$.)

If you want a formula for how to round you can use $lfloor rfloor$ and function. If $k - lfloor k rfloor < frac 12$ then $round(k) = lfloor k rfloor$. If $k - lfloor k rfloor ge frac 12$ then $round (k) = lfloor k rfloor + 1$

So rounding $A$ to the nearest $m$ is

$mtimes($ if $lfloor frac Am rfloor < frac 12$ then $lfloor frac Am rfloor$; else $lfloor frac Am rfloor + 1)$

In the case of $m = 0.05$ it is

$0.05times ($ if $20A - lfloor 20A rfloor < frac 12$ then $lfloor 20A rfloor$; else $lfloor 20A rfloor + 1)$.

So to round $1,459.98$

$0.05times ($ if $20*1,459.98-lfloor 20*1,459.98 rfloor < frac 12$ then $lfloor 20*1,459.98 rfloor$; else $lfloor 20*1,459.98 rfloor + 1)=$

$0.05times ($ if $29199.6 -lfloor 29199.6 rfloor < frac 12$ then $lfloor 29199.6 rfloor$; else $lfloor 29199.6 rfloor + 1)=$

$0.05times ($ if $29199.6 - 29199 < frac 12$ then $29199 $; else $ 29199 + 1)=$

$0.05times ($ if $0.6 < frac 12$ then $29199 $; else $29200)=$

$0.05times (29200)=1460.00$