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	$187.46	11.495%	$209.0085	$209.01	$209.00	$209.00
Purchase #2	$96.30	3.795%	$99.9546	$99.95	$99.95	$100.00
Purchase #3	$35.88	7.785%	$38.6733	$38.67	$38.65	$38.70
Purchase #4	$214.57	3.503%	$222.0864	$222.09	$222.10	$222.10
Purchase #5	$238.79	12.226%	$267.9845	$267.98	$268.00	$268.00
Purchase #6	$52.71	13.545%	$59.8496	$59.85	$59.85	$59.80
Purchase #7	$114.52	11.276%	$127.4333	$127.43	$127.45	$127.40
7 purchase totals =	$940.23		$1,024.9902	$1,024.98	$1,025.00	$1,025.00