Fix bug on parsing coin amount and converting to int coins

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@initia/initia.js",
-  "version": "0.2.26",
+  "version": "0.2.27",
   "description": "The JavaScript SDK for Initia",
   "license": "Apache-2.0",
   "author": "Initia Foundation",

src/core/Coin.ts

@@ -1,6 +1,6 @@
 import { JSONSerializable } from '../util/json'
 import { Denom } from './Denom'
-import { num, checkDecimal } from './num'
+import { num, checkDecimal, BigNumber } from './num'
 import { Coin as Coin_pb } from '@initia/initia.proto/cosmos/base/v1beta1/coin'
 
 /**
@@ -23,22 +23,22 @@ export class Coin extends JSONSerializable<Coin.Amino, Coin.Data, Coin.Proto> {
     amount: number | string
   ) {
     super()
-    this.amount = num(amount).toString()
+    this.amount = num(amount).toFixed()
     this.isDecimal = checkDecimal(amount)
   }
 
   /**
    * Turns the Coin into an Integer coin.
    */
   public toIntCoin(): Coin {
-    return new Coin(this.denom, num(this.amount).toFixed())
+    return new Coin(this.denom, num(this.amount).toFixed(0))
   }
 
   /**
    * Turns the Coin into an Integer coin with ceiling the amount.
    */
   public toIntCeilCoin(): Coin {
-    return new Coin(this.denom, num(this.amount).toFixed(0, 2))
+    return new Coin(this.denom, num(this.amount).toFixed(0, BigNumber.ROUND_CEIL))
   }
 
   /**