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	$175.58	11.641%	$196.0193	$196.02	$196.00	$196.00
Purchase #2	$119.85	6.708%	$127.8895	$127.89	$127.90	$127.90
Purchase #3	$180.57	6.726%	$192.7151	$192.72	$192.70	$192.70
Purchase #4	$218.27	5.249%	$229.727	$229.73	$229.75	$229.70
Purchase #5	$53.36	8.371%	$57.8268	$57.83	$57.85	$57.80
Purchase #6	$44.79	8.290%	$48.5031	$48.50	$48.50	$48.50
Purchase #7	$248.91	5.367%	$262.269	$262.27	$262.25	$262.30
7 purchase totals =	$1,041.33		$1,114.9498	$1,114.96	$1,114.95	$1,114.90