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	$198.34	12.432%	$222.9976	$223.00	$223.00	$223.00
Purchase #2	$59.28	5.242%	$62.3875	$62.39	$62.40	$62.40
Purchase #3	$191.28	4.548%	$199.9794	$199.98	$200.00	$200.00
Purchase #4	$171.43	9.106%	$187.0404	$187.04	$187.05	$187.00
Purchase #5	$62.52	6.119%	$66.3456	$66.35	$66.35	$66.30
Purchase #6	$128.27	13.866%	$146.0559	$146.06	$146.05	$146.10
Purchase #7	$167.98	3.690%	$174.1785	$174.18	$174.20	$174.20
7 purchase totals =	$979.10		$1,058.9849	$1,059.00	$1,059.05	$1,059.00