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	$230.80	13.582%	$262.1473	$262.15	$262.15	$262.10
Purchase #2	$69.41	5.147%	$72.9825	$72.98	$73.00	$73.00
Purchase #3	$164.85	9.589%	$180.6575	$180.66	$180.65	$180.70
Purchase #4	$78.42	4.643%	$82.061	$82.06	$82.05	$82.10
Purchase #5	$24.67	7.688%	$26.5666	$26.57	$26.55	$26.60
Purchase #6	$190.51	3.310%	$196.8159	$196.82	$196.80	$196.80
Purchase #7	$230.32	10.205%	$253.8242	$253.82	$253.80	$253.80
7 purchase totals =	$988.98		$1,075.0550	$1,075.06	$1,075.00	$1,075.10