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	$174.71	5.476%	$184.2771	$184.28	$184.30	$184.30
Purchase #2	$58.86	3.499%	$60.9195	$60.92	$60.90	$60.90
Purchase #3	$75.31	9.503%	$82.4667	$82.47	$82.45	$82.50
Purchase #4	$171.72	10.605%	$189.9309	$189.93	$189.95	$189.90
Purchase #5	$31.59	7.496%	$33.958	$33.96	$33.95	$34.00
Purchase #6	$57.28	13.151%	$64.8129	$64.81	$64.80	$64.80
Purchase #7	$88.75	13.242%	$100.5023	$100.50	$100.50	$100.50
7 purchase totals =	$658.22		$716.8674	$716.87	$716.85	$716.90