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	$196.96	12.791%	$222.1532	$222.15	$222.15	$222.20
Purchase #2	$40.28	7.618%	$43.3485	$43.35	$43.35	$43.30
Purchase #3	$143.53	7.873%	$154.8301	$154.83	$154.85	$154.80
Purchase #4	$209.29	12.757%	$235.9891	$235.99	$236.00	$236.00
Purchase #5	$66.47	7.184%	$71.2452	$71.25	$71.25	$71.20
Purchase #6	$153.65	4.601%	$160.7194	$160.72	$160.70	$160.70
Purchase #7	$181.95	7.812%	$196.1639	$196.16	$196.15	$196.20
7 purchase totals =	$992.13		$1,084.4494	$1,084.45	$1,084.45	$1,084.40