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	$114.25	11.277%	$127.134	$127.13	$127.15	$127.10
Purchase #2	$183.77	13.527%	$208.6286	$208.63	$208.65	$208.60
Purchase #3	$187.78	4.689%	$196.585	$196.59	$196.60	$196.60
Purchase #4	$195.67	7.857%	$211.0438	$211.04	$211.05	$211.00
Purchase #5	$170.29	12.718%	$191.9475	$191.95	$191.95	$191.90
Purchase #6	$177.53	10.678%	$196.4867	$196.49	$196.50	$196.50
Purchase #7	$145.58	7.608%	$156.6557	$156.66	$156.65	$156.70
7 purchase totals =	$1,174.87		$1,288.4813	$1,288.49	$1,288.55	$1,288.40