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	$140.34	9.387%	$153.5137	$153.51	$153.50	$153.50
Purchase #2	$61.49	7.655%	$66.1971	$66.20	$66.20	$66.20
Purchase #3	$182.57	7.747%	$196.7137	$196.71	$196.70	$196.70
Purchase #4	$175.70	5.426%	$185.2335	$185.23	$185.25	$185.20
Purchase #5	$128.66	11.271%	$143.1613	$143.16	$143.15	$143.20
Purchase #6	$96.40	9.542%	$105.5985	$105.60	$105.60	$105.60
Purchase #7	$180.79	9.316%	$197.6324	$197.63	$197.65	$197.60
7 purchase totals =	$965.95		$1,048.0502	$1,048.04	$1,048.05	$1,048.00