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	$168.89	9.801%	$185.4429	$185.44	$185.45	$185.40
Purchase #2	$231.56	11.324%	$257.7819	$257.78	$257.80	$257.80
Purchase #3	$194.51	13.319%	$220.4168	$220.42	$220.40	$220.40
Purchase #4	$51.86	6.847%	$55.4109	$55.41	$55.40	$55.40
Purchase #5	$39.72	13.447%	$45.0611	$45.06	$45.05	$45.10
Purchase #6	$179.57	9.192%	$196.0761	$196.08	$196.10	$196.10
Purchase #7	$49.43	10.402%	$54.5717	$54.57	$54.55	$54.60
7 purchase totals =	$915.54		$1,014.7614	$1,014.76	$1,014.75	$1,014.80