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	$174.73	9.613%	$191.5268	$191.53	$191.55	$191.50
Purchase #2	$83.80	10.507%	$92.6049	$92.60	$92.60	$92.60
Purchase #3	$62.98	3.122%	$64.9462	$64.95	$64.95	$64.90
Purchase #4	$122.50	11.510%	$136.5998	$136.60	$136.60	$136.60
Purchase #5	$162.48	4.353%	$169.5528	$169.55	$169.55	$169.60
Purchase #6	$214.29	7.247%	$229.8196	$229.82	$229.80	$229.80
Purchase #7	$141.48	5.212%	$148.8539	$148.85	$148.85	$148.90
7 purchase totals =	$962.26		$1,033.9040	$1,033.90	$1,033.90	$1,033.90