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	$220.33	8.180%	$238.353	$238.35	$238.35	$238.40
Purchase #2	$76.79	10.490%	$84.8453	$84.85	$84.85	$84.80
Purchase #3	$136.83	11.452%	$152.4998	$152.50	$152.50	$152.50
Purchase #4	$244.68	10.755%	$270.9953	$271.00	$271.00	$271.00
Purchase #5	$101.39	5.797%	$107.2676	$107.27	$107.25	$107.30
Purchase #6	$59.27	4.461%	$61.914	$61.91	$61.90	$61.90
Purchase #7	$181.72	10.184%	$200.2264	$200.23	$200.25	$200.20
7 purchase totals =	$1,021.01		$1,116.1014	$1,116.11	$1,116.10	$1,116.10