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	$93.43	10.616%	$103.3485	$103.35	$103.35	$103.30
Purchase #2	$203.26	9.855%	$223.2913	$223.29	$223.30	$223.30
Purchase #3	$177.53	13.507%	$201.509	$201.51	$201.50	$201.50
Purchase #4	$203.57	5.123%	$213.9989	$214.00	$214.00	$214.00
Purchase #5	$141.61	7.334%	$151.9957	$152.00	$152.00	$152.00
Purchase #6	$90.55	10.272%	$99.8513	$99.85	$99.85	$99.90
Purchase #7	$59.47	3.263%	$61.4105	$61.41	$61.40	$61.40
7 purchase totals =	$969.42		$1,055.4052	$1,055.41	$1,055.40	$1,055.40