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	$160.37	9.198%	$175.1208	$175.12	$175.10	$175.10
Purchase #2	$134.69	13.405%	$152.7452	$152.75	$152.75	$152.70
Purchase #3	$57.53	8.594%	$62.4741	$62.47	$62.45	$62.50
Purchase #4	$14.47	3.454%	$14.9698	$14.97	$14.95	$15.00
Purchase #5	$237.68	7.838%	$256.3094	$256.31	$256.30	$256.30
Purchase #6	$222.42	12.142%	$249.4262	$249.43	$249.45	$249.40
Purchase #7	$94.59	9.369%	$103.4521	$103.45	$103.45	$103.50
7 purchase totals =	$921.75		$1,014.4976	$1,014.50	$1,014.45	$1,014.50