Just change the Item ID's.
prontera,138,181,5, script Trader 828,{
set .bronze,555;//item id of bronze
set .gold,555;//item id of gold
set .platinum,555;//item id of platinum
set .poringcoin,555;//item id of poring coin
set @header$,"[^0000ff Trader ^000000]";//NPC Name
mes @header$;
mes "Hello";
menu "5 Bronze to 1Gold",-,"5 Gold to 1 Platinum",gtp,"5 Platinum to 1 Poring Coin",ptp;
if(countitem(.bronze) < 5) goto L_NOTENOUGH;
next;
mes @header$;
mes "Thanks. . See you again. . . !";
delitem .bronze,5;
getitem .gold,1;
close;
gtp:
if(countitem(.gold) < 5) goto L_NOTENOUGH;
next;
mes @header$;
mes "Thanks. . See you again. . . !";
delitem .gold,5;
getitem .platinum,1;
close;
ptp:
if(countitem(.gold) < 5) goto L_NOTENOUGH;
next;
mes @header$;
mes "Thanks. . See you again. . . !";
delitem .gold,5;
getitem .poringcoin,1;
close;
L_NOTENOUGH:
next;
mes @header$;
mes "Not enough requirements";
close;
}