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	$146.65	10.713%	$162.3606	$162.36	$162.35	$162.40
Purchase #2	$222.82	4.806%	$233.5287	$233.53	$233.55	$233.50
Purchase #3	$40.95	11.595%	$45.6982	$45.70	$45.70	$45.70
Purchase #4	$55.90	6.442%	$59.5011	$59.50	$59.50	$59.50
Purchase #5	$100.29	9.186%	$109.5026	$109.50	$109.50	$109.50
Purchase #6	$203.88	10.481%	$225.2487	$225.25	$225.25	$225.20
Purchase #7	$104.61	5.158%	$110.0058	$110.01	$110.00	$110.00
7 purchase totals =	$875.10		$945.8457	$945.85	$945.85	$945.80