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	$162.32	8.737%	$176.5019	$176.50	$176.50	$176.50
Purchase #2	$202.58	10.223%	$223.2898	$223.29	$223.30	$223.30
Purchase #3	$161.29	3.859%	$167.5142	$167.51	$167.50	$167.50
Purchase #4	$188.66	8.727%	$205.1244	$205.12	$205.10	$205.10
Purchase #5	$187.74	6.637%	$200.2003	$200.20	$200.20	$200.20
Purchase #6	$193.99	12.325%	$217.8993	$217.90	$217.90	$217.90
Purchase #7	$187.69	4.857%	$196.8061	$196.81	$196.80	$196.80
7 purchase totals =	$1,284.27		$1,387.3360	$1,387.33	$1,387.30	$1,387.30