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	$148.92	10.742%	$164.917	$164.92	$164.90	$164.90
Purchase #2	$127.97	12.304%	$143.7154	$143.72	$143.70	$143.70
Purchase #3	$67.39	3.323%	$69.6294	$69.63	$69.65	$69.60
Purchase #4	$164.79	9.770%	$180.89	$180.89	$180.90	$180.90
Purchase #5	$223.60	8.843%	$243.3729	$243.37	$243.35	$243.40
Purchase #6	$228.76	11.449%	$254.9507	$254.95	$254.95	$255.00
Purchase #7	$53.45	6.474%	$56.9104	$56.91	$56.90	$56.90
7 purchase totals =	$1,014.88		$1,114.3858	$1,114.39	$1,114.35	$1,114.40