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	$119.33	10.401%	$131.7415	$131.74	$131.75	$131.70
Purchase #2	$13.54	5.373%	$14.2675	$14.27	$14.25	$14.30
Purchase #3	$227.96	3.728%	$236.4583	$236.46	$236.45	$236.50
Purchase #4	$82.29	11.303%	$91.5912	$91.59	$91.60	$91.60
Purchase #5	$17.64	13.672%	$20.0517	$20.05	$20.05	$20.10
Purchase #6	$141.96	8.161%	$153.5454	$153.55	$153.55	$153.50
Purchase #7	$64.75	5.408%	$68.2517	$68.25	$68.25	$68.30
7 purchase totals =	$667.47		$715.9073	$715.91	$715.90	$716.00