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	$59.73	3.623%	$61.894	$61.89	$61.90	$61.90
Purchase #2	$85.57	9.850%	$93.9986	$94.00	$94.00	$94.00
Purchase #3	$74.34	5.356%	$78.3217	$78.32	$78.30	$78.30
Purchase #4	$182.43	7.853%	$196.7562	$196.76	$196.75	$196.80
Purchase #5	$161.79	4.494%	$169.0608	$169.06	$169.05	$169.10
Purchase #6	$241.68	11.514%	$269.507	$269.51	$269.50	$269.50
Purchase #7	$98.70	7.509%	$106.1114	$106.11	$106.10	$106.10
7 purchase totals =	$904.24		$975.6497	$975.65	$975.60	$975.70