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	$140.60	7.313%	$150.8821	$150.88	$150.90	$150.90
Purchase #2	$9.84	9.306%	$10.7557	$10.76	$10.75	$10.80
Purchase #3	$163.78	4.709%	$171.4924	$171.49	$171.50	$171.50
Purchase #4	$210.36	8.822%	$228.918	$228.92	$228.90	$228.90
Purchase #5	$108.30	3.168%	$111.7309	$111.73	$111.75	$111.70
Purchase #6	$145.74	13.291%	$165.1103	$165.11	$165.10	$165.10
Purchase #7	$200.43	4.822%	$210.0947	$210.09	$210.10	$210.10
7 purchase totals =	$979.05		$1,048.9841	$1,048.98	$1,049.00	$1,049.00