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	$233.92	12.812%	$263.8898	$263.89	$263.90	$263.90
Purchase #2	$10.75	11.686%	$12.0062	$12.01	$12.00	$12.00
Purchase #3	$185.96	5.674%	$196.5114	$196.51	$196.50	$196.50
Purchase #4	$223.61	4.731%	$234.189	$234.19	$234.20	$234.20
Purchase #5	$60.34	5.421%	$63.611	$63.61	$63.60	$63.60
Purchase #6	$179.96	9.500%	$197.0562	$197.06	$197.05	$197.10
Purchase #7	$80.98	12.152%	$90.8207	$90.82	$90.80	$90.80
7 purchase totals =	$975.52		$1,058.0843	$1,058.09	$1,058.05	$1,058.10