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	$196.44	13.425%	$222.8121	$222.81	$222.80	$222.80
Purchase #2	$201.86	10.356%	$222.7646	$222.76	$222.75	$222.80
Purchase #3	$219.42	13.296%	$248.5941	$248.59	$248.60	$248.60
Purchase #4	$190.40	9.480%	$208.4499	$208.45	$208.45	$208.40
Purchase #5	$42.41	10.227%	$46.7473	$46.75	$46.75	$46.70
Purchase #6	$159.54	10.860%	$176.866	$176.87	$176.85	$176.90
Purchase #7	$161.78	3.681%	$167.7351	$167.74	$167.75	$167.70
7 purchase totals =	$1,171.85		$1,293.9691	$1,293.97	$1,293.95	$1,293.90