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	$191.62	12.665%	$215.8887	$215.89	$215.90	$215.90
Purchase #2	$160.64	13.237%	$181.9039	$181.90	$181.90	$181.90
Purchase #3	$171.37	13.578%	$194.6386	$194.64	$194.65	$194.60
Purchase #4	$61.61	8.322%	$66.7372	$66.74	$66.75	$66.70
Purchase #5	$131.41	8.124%	$142.0857	$142.09	$142.10	$142.10
Purchase #6	$72.67	10.328%	$80.1754	$80.18	$80.20	$80.20
Purchase #7	$156.85	5.535%	$165.5316	$165.53	$165.55	$165.50
7 purchase totals =	$946.17		$1,046.9611	$1,046.97	$1,047.05	$1,046.90