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	$152.46	5.568%	$160.949	$160.95	$160.95	$160.90
Purchase #2	$96.59	5.676%	$102.0724	$102.07	$102.05	$102.10
Purchase #3	$159.78	4.552%	$167.0532	$167.05	$167.05	$167.10
Purchase #4	$176.75	13.647%	$200.8711	$200.87	$200.85	$200.90
Purchase #5	$206.68	5.838%	$218.746	$218.75	$218.75	$218.70
Purchase #6	$80.69	8.581%	$87.614	$87.61	$87.60	$87.60
Purchase #7	$63.38	12.373%	$71.222	$71.22	$71.20	$71.20
7 purchase totals =	$936.33		$1,008.5277	$1,008.52	$1,008.45	$1,008.50