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	$71.30	7.340%	$76.5334	$76.53	$76.55	$76.50
Purchase #2	$176.63	10.534%	$195.2362	$195.24	$195.25	$195.20
Purchase #3	$177.67	10.591%	$196.487	$196.49	$196.50	$196.50
Purchase #4	$111.91	5.845%	$118.4511	$118.45	$118.45	$118.50
Purchase #5	$134.59	12.335%	$151.1917	$151.19	$151.20	$151.20
Purchase #6	$55.55	7.621%	$59.7835	$59.78	$59.80	$59.80
Purchase #7	$209.51	10.707%	$231.9422	$231.94	$231.95	$231.90
7 purchase totals =	$937.16		$1,029.6251	$1,029.62	$1,029.70	$1,029.60