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	$156.56	7.151%	$167.7556	$167.76	$167.75	$167.80
Purchase #2	$108.94	3.523%	$112.778	$112.78	$112.80	$112.80
Purchase #3	$144.33	9.742%	$158.3906	$158.39	$158.40	$158.40
Purchase #4	$63.81	5.311%	$67.1989	$67.20	$67.20	$67.20
Purchase #5	$139.37	4.780%	$146.0319	$146.03	$146.05	$146.00
Purchase #6	$238.55	12.873%	$269.2585	$269.26	$269.25	$269.30
Purchase #7	$97.68	3.373%	$100.9747	$100.97	$100.95	$101.00
7 purchase totals =	$949.24		$1,022.3882	$1,022.39	$1,022.40	$1,022.50