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	$205.73	13.476%	$233.4542	$233.45	$233.45	$233.50
Purchase #2	$106.39	5.732%	$112.4883	$112.49	$112.50	$112.50
Purchase #3	$49.89	5.532%	$52.6499	$52.65	$52.65	$52.60
Purchase #4	$28.70	7.597%	$30.8803	$30.88	$30.90	$30.90
Purchase #5	$152.49	13.749%	$173.4559	$173.46	$173.45	$173.50
Purchase #6	$245.52	5.759%	$259.6595	$259.66	$259.65	$259.70
Purchase #7	$146.25	8.593%	$158.8173	$158.82	$158.80	$158.80
7 purchase totals =	$934.97		$1,021.4054	$1,021.41	$1,021.40	$1,021.50