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	$114.31	11.654%	$127.6317	$127.63	$127.65	$127.60
Purchase #2	$165.40	6.551%	$176.2354	$176.24	$176.25	$176.20
Purchase #3	$227.66	3.494%	$235.6144	$235.61	$235.60	$235.60
Purchase #4	$219.66	10.516%	$242.7594	$242.76	$242.75	$242.80
Purchase #5	$100.43	9.135%	$109.6043	$109.60	$109.60	$109.60
Purchase #6	$158.99	10.383%	$175.4979	$175.50	$175.50	$175.50
Purchase #7	$26.67	4.590%	$27.8942	$27.89	$27.90	$27.90
7 purchase totals =	$1,013.12		$1,095.2373	$1,095.23	$1,095.25	$1,095.20