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	$172.94	13.492%	$196.2731	$196.27	$196.25	$196.30
Purchase #2	$22.92	12.374%	$25.7561	$25.76	$25.75	$25.80
Purchase #3	$52.88	12.871%	$59.6862	$59.69	$59.70	$59.70
Purchase #4	$200.71	9.505%	$219.7875	$219.79	$219.80	$219.80
Purchase #5	$160.25	12.619%	$180.4719	$180.47	$180.45	$180.50
Purchase #6	$203.84	13.304%	$230.9589	$230.96	$230.95	$231.00
Purchase #7	$147.50	10.273%	$162.6527	$162.65	$162.65	$162.70
7 purchase totals =	$961.04		$1,075.5864	$1,075.59	$1,075.55	$1,075.80