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	$48.57	10.299%	$53.5722	$53.57	$53.55	$53.60
Purchase #2	$99.54	12.388%	$111.871	$111.87	$111.85	$111.90
Purchase #3	$181.34	8.435%	$196.636	$196.64	$196.65	$196.60
Purchase #4	$244.92	4.423%	$255.7528	$255.75	$255.75	$255.80
Purchase #5	$245.27	8.478%	$266.064	$266.06	$266.05	$266.10
Purchase #6	$5.71	6.473%	$6.0796	$6.08	$6.10	$6.10
Purchase #7	$148.45	5.857%	$157.1447	$157.14	$157.15	$157.10
7 purchase totals =	$973.80		$1,047.1203	$1,047.11	$1,047.10	$1,047.20