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	$176.54	8.503%	$191.5512	$191.55	$191.55	$191.60
Purchase #2	$196.26	4.769%	$205.6196	$205.62	$205.60	$205.60
Purchase #3	$162.62	3.133%	$167.7149	$167.71	$167.70	$167.70
Purchase #4	$49.92	4.217%	$52.0251	$52.03	$52.05	$52.00
Purchase #5	$200.45	7.336%	$215.155	$215.16	$215.15	$215.20
Purchase #6	$141.42	7.518%	$152.052	$152.05	$152.05	$152.10
Purchase #7	$99.27	3.184%	$102.4308	$102.43	$102.45	$102.40
7 purchase totals =	$1,026.48		$1,086.5486	$1,086.55	$1,086.55	$1,086.60