its usually just a glitch with the decimal conversions of the price
basically TBT bells work in decimal form but they don't actually show up in decimal form. Eg, you could have 56.6 bells, and it'd round it up to 57 - but if you try bought something from the shop that was 57 bells then it wouldn't let you buy it because in reality you are .4 bells short.
not sure why it did the same with you since usually adding an extra bell works (since it rounds it up a higher) but if you withdrew a few more it should work