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	$189.40	3.813%	$196.6218	$196.62	$196.60	$196.60
Purchase #2	$31.45	7.576%	$33.8327	$33.83	$33.85	$33.80
Purchase #3	$110.30	3.788%	$114.4782	$114.48	$114.50	$114.50
Purchase #4	$142.71	5.593%	$150.6918	$150.69	$150.70	$150.70
Purchase #5	$190.94	11.283%	$212.4838	$212.48	$212.50	$212.50
Purchase #6	$223.81	13.626%	$254.3064	$254.31	$254.30	$254.30
Purchase #7	$56.64	9.755%	$62.1652	$62.17	$62.15	$62.20
7 purchase totals =	$945.25		$1,024.5799	$1,024.58	$1,024.60	$1,024.60