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	$175.43	11.681%	$195.922	$195.92	$195.90	$195.90
Purchase #2	$111.38	6.488%	$118.6063	$118.61	$118.60	$118.60
Purchase #3	$163.49	10.471%	$180.609	$180.61	$180.60	$180.60
Purchase #4	$226.25	11.300%	$251.8163	$251.82	$251.80	$251.80
Purchase #5	$106.33	3.317%	$109.857	$109.86	$109.85	$109.90
Purchase #6	$136.54	5.375%	$143.879	$143.88	$143.90	$143.90
Purchase #7	$106.40	7.502%	$114.3821	$114.38	$114.40	$114.40
7 purchase totals =	$1,025.82		$1,115.0717	$1,115.08	$1,115.05	$1,115.10