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	$36.92	11.206%	$41.0573	$41.06	$41.05	$41.10
Purchase #2	$36.86	4.414%	$38.487	$38.49	$38.50	$38.50
Purchase #3	$183.72	13.227%	$208.0206	$208.02	$208.00	$208.00
Purchase #4	$191.88	10.775%	$212.5551	$212.56	$212.55	$212.60
Purchase #5	$194.54	13.414%	$220.6356	$220.64	$220.65	$220.60
Purchase #6	$215.25	3.680%	$223.1712	$223.17	$223.15	$223.20
Purchase #7	$190.72	10.637%	$211.0069	$211.01	$211.00	$211.00
7 purchase totals =	$1,049.89		$1,154.9337	$1,154.95	$1,154.90	$1,155.00