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	$62.32	11.437%	$69.4475	$69.45	$69.45	$69.40
Purchase #2	$195.76	4.248%	$204.0759	$204.08	$204.10	$204.10
Purchase #3	$49.52	9.154%	$54.0531	$54.05	$54.05	$54.10
Purchase #4	$246.96	5.719%	$261.0836	$261.08	$261.10	$261.10
Purchase #5	$190.72	11.823%	$213.2688	$213.27	$213.25	$213.30
Purchase #6	$71.61	9.751%	$78.5927	$78.59	$78.60	$78.60
Purchase #7	$49.83	9.251%	$54.4398	$54.44	$54.45	$54.40
7 purchase totals =	$866.72		$934.9614	$934.96	$935.00	$935.00