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	$56.79	4.644%	$59.4273	$59.43	$59.45	$59.40
Purchase #2	$57.53	13.855%	$65.5008	$65.50	$65.50	$65.50
Purchase #3	$205.34	3.214%	$211.9396	$211.94	$211.95	$211.90
Purchase #4	$211.49	9.812%	$232.2414	$232.24	$232.25	$232.20
Purchase #5	$168.80	12.350%	$189.6468	$189.65	$189.65	$189.60
Purchase #6	$56.68	5.562%	$59.8325	$59.83	$59.85	$59.80
Purchase #7	$198.49	7.480%	$213.3371	$213.34	$213.35	$213.30
7 purchase totals =	$955.12		$1,031.9255	$1,031.93	$1,032.00	$1,031.70