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	$53.71	10.127%	$59.1492	$59.15	$59.15	$59.10
Purchase #2	$64.81	11.617%	$72.339	$72.34	$72.35	$72.30
Purchase #3	$133.51	3.483%	$138.1602	$138.16	$138.15	$138.20
Purchase #4	$175.94	12.330%	$197.6334	$197.63	$197.65	$197.60
Purchase #5	$224.27	12.649%	$252.6379	$252.64	$252.65	$252.60
Purchase #6	$17.82	9.227%	$19.4643	$19.46	$19.45	$19.50
Purchase #7	$217.57	7.501%	$233.8899	$233.89	$233.90	$233.90
7 purchase totals =	$887.63		$973.2739	$973.27	$973.30	$973.20