Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$174.47	12.725%	$196.6713	$196.67	$196.65	$196.70
Purchase #2	$139.96	10.125%	$154.131	$154.13	$154.15	$154.10
Purchase #3	$192.48	9.699%	$211.1486	$211.15	$211.15	$211.10
Purchase #4	$11.38	5.862%	$12.0471	$12.05	$12.05	$12.00
Purchase #5	$93.88	12.324%	$105.4498	$105.45	$105.45	$105.40
Purchase #6	$212.32	4.316%	$221.4837	$221.48	$221.50	$221.50
Purchase #7	$148.62	10.419%	$164.1047	$164.10	$164.10	$164.10
7 purchase totals =	$973.11		$1,065.0362	$1,065.03	$1,065.05	$1,064.90