said by EUS:So rounding should only be applied to change dispersed, not the invoiced amount.
It doesn't make any difference. You can round the
final amount, after all taxes and everything else are applied. Something sells for 99 cents. 99 cents plus HST is $1.12. You don't round the 99 cents to $1 before adding tax, you round the $1.12 down to $1.10.
For accounting purposes, the invoice would be posted to your revenue account for 99 cents and your HST paid on sales account for 12 cents. The payment would be posted as a $1.10 debit to your cash received account and two cents would then be debited to a rounding or cash short/over account. The customer would owe you $1.10, you'd give them change, everyone is happy.
If the item was $1 rather than 99 cents and the total after tax was $1.13 you would do the same thing, post $1 to revenue and 13 cents to HST paid on sales. $1.15 would be debited to your cash received account and two cents would be credited to your short/over account. The customer would give you $1.15, you'd give them their change and all is swell.
The short/over account
should be near zero by the time year end comes around.