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	$82.69	3.670%	$85.7247	$85.72	$85.70	$85.70
Purchase #2	$85.58	4.493%	$89.4251	$89.43	$89.45	$89.40
Purchase #3	$44.39	7.868%	$47.8826	$47.88	$47.90	$47.90
Purchase #4	$190.97	10.534%	$211.0868	$211.09	$211.10	$211.10
Purchase #5	$181.89	13.216%	$205.9286	$205.93	$205.95	$205.90
Purchase #6	$196.79	13.172%	$222.7112	$222.71	$222.70	$222.70
Purchase #7	$199.60	6.558%	$212.6898	$212.69	$212.70	$212.70
7 purchase totals =	$981.91		$1,075.4488	$1,075.45	$1,075.50	$1,075.40