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	$154.99	5.562%	$163.6105	$163.61	$163.60	$163.60
Purchase #2	$247.96	5.443%	$261.4565	$261.46	$261.45	$261.50
Purchase #3	$104.38	7.250%	$111.9476	$111.95	$111.95	$111.90
Purchase #4	$53.87	7.350%	$57.8294	$57.83	$57.85	$57.80
Purchase #5	$220.98	3.507%	$228.7298	$228.73	$228.75	$228.70
Purchase #6	$244.48	11.632%	$272.9179	$272.92	$272.90	$272.90
Purchase #7	$104.77	4.111%	$109.0771	$109.08	$109.10	$109.10
7 purchase totals =	$1,131.43		$1,205.5688	$1,205.58	$1,205.60	$1,205.50