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	$70.43	7.521%	$75.727	$75.73	$75.75	$75.70
Purchase #2	$196.93	8.517%	$213.7025	$213.70	$213.70	$213.70
Purchase #3	$17.50	9.275%	$19.1231	$19.12	$19.10	$19.10
Purchase #4	$174.86	8.395%	$189.5395	$189.54	$189.55	$189.50
Purchase #5	$228.25	5.615%	$241.0662	$241.07	$241.05	$241.10
Purchase #6	$173.76	13.314%	$196.8944	$196.89	$196.90	$196.90
Purchase #7	$150.64	3.820%	$156.3944	$156.39	$156.40	$156.40
7 purchase totals =	$1,012.37		$1,092.4471	$1,092.44	$1,092.45	$1,092.40