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	$104.30	3.497%	$107.9474	$107.95	$107.95	$107.90
Purchase #2	$102.95	6.769%	$109.9187	$109.92	$109.90	$109.90
Purchase #3	$225.86	4.308%	$235.59	$235.59	$235.60	$235.60
Purchase #4	$160.92	7.469%	$172.9391	$172.94	$172.95	$172.90
Purchase #5	$10.78	7.856%	$11.6269	$11.63	$11.65	$11.60
Purchase #6	$203.73	9.472%	$223.0273	$223.03	$223.05	$223.00
Purchase #7	$207.51	5.802%	$219.5497	$219.55	$219.55	$219.50
7 purchase totals =	$1,016.05		$1,080.5991	$1,080.61	$1,080.65	$1,080.40