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	$48.40	7.336%	$51.9506	$51.95	$51.95	$52.00
Purchase #2	$170.56	8.734%	$185.4567	$185.46	$185.45	$185.50
Purchase #3	$182.34	7.759%	$196.4878	$196.49	$196.50	$196.50
Purchase #4	$10.28	9.212%	$11.227	$11.23	$11.25	$11.20
Purchase #5	$23.36	8.158%	$25.2657	$25.27	$25.25	$25.30
Purchase #6	$143.71	6.778%	$153.4507	$153.45	$153.45	$153.50
Purchase #7	$226.74	5.625%	$239.4941	$239.49	$239.50	$239.50
7 purchase totals =	$805.39		$863.3326	$863.34	$863.35	$863.50