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	$197.78	8.587%	$214.7634	$214.76	$214.75	$214.80
Purchase #2	$160.48	11.647%	$179.1711	$179.17	$179.15	$179.20
Purchase #3	$191.88	5.715%	$202.8459	$202.85	$202.85	$202.80
Purchase #4	$19.46	5.112%	$20.4548	$20.45	$20.45	$20.50
Purchase #5	$167.69	4.445%	$175.1438	$175.14	$175.15	$175.10
Purchase #6	$46.69	12.186%	$52.3796	$52.38	$52.40	$52.40
Purchase #7	$55.51	7.816%	$59.8487	$59.85	$59.85	$59.80
7 purchase totals =	$839.49		$904.6073	$904.60	$904.60	$904.60