Please tell me how to round off the Rails app's consumption tax decimal point.

The view has item name, quantity, and unit price.
If the quantity is "1" and the unit price is "485,560", the consumption tax is "38,844.8->38,845"
If the quantity is '-1' and the unit price is '485,560', the consumption tax is '38,844.8->38,844'
The amount of consumption tax will be different.
I'd like to round off the consumption tax to 38,845; what should I do?
Thank you very much for your information.

<p class="pill-left total_fee_wrapper_02"><span class="total_fee_background tax_border_left total_fee_font_size_02">消費税額</span>¥<span class="total_fee total_fee_font_size"><%= number_with_delimiter((BigDecimal(@selling_price_total_07.to_i + @selling_price_total_15.to_i + @selling_price_total_37.to_i + @selling_price_total_52.to_i)*BigDecimal(@tax))).ceil)%></span>/p>