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	$57.76	8.538%	$62.6915	$62.69	$62.70	$62.70
Purchase #2	$73.96	6.729%	$78.9368	$78.94	$78.95	$78.90
Purchase #3	$89.58	8.796%	$97.4595	$97.46	$97.45	$97.50
Purchase #4	$191.81	9.148%	$209.3568	$209.36	$209.35	$209.40
Purchase #5	$210.68	6.767%	$224.9367	$224.94	$224.95	$224.90
Purchase #6	$160.39	5.389%	$169.0334	$169.03	$169.05	$169.00
Purchase #7	$168.86	12.840%	$190.5416	$190.54	$190.55	$190.50
7 purchase totals =	$953.04		$1,032.9563	$1,032.96	$1,033.00	$1,032.90