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	$192.31	11.499%	$214.4237	$214.42	$214.40	$214.40
Purchase #2	$140.64	13.419%	$159.5125	$159.51	$159.50	$159.50
Purchase #3	$68.79	3.682%	$71.3228	$71.32	$71.30	$71.30
Purchase #4	$192.38	8.800%	$209.3094	$209.31	$209.30	$209.30
Purchase #5	$188.85	12.565%	$212.579	$212.58	$212.60	$212.60
Purchase #6	$68.61	4.221%	$71.506	$71.51	$71.50	$71.50
Purchase #7	$225.63	3.548%	$233.6354	$233.64	$233.65	$233.60
7 purchase totals =	$1,077.21		$1,172.2888	$1,172.29	$1,172.25	$1,172.20