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	$184.90	9.213%	$201.9348	$201.93	$201.95	$201.90
Purchase #2	$170.53	3.720%	$176.8737	$176.87	$176.85	$176.90
Purchase #3	$162.66	11.208%	$180.8909	$180.89	$180.90	$180.90
Purchase #4	$144.54	10.603%	$159.8656	$159.87	$159.85	$159.90
Purchase #5	$50.35	7.463%	$54.1076	$54.11	$54.10	$54.10
Purchase #6	$196.64	13.601%	$223.385	$223.39	$223.40	$223.40
Purchase #7	$137.46	5.110%	$144.4842	$144.48	$144.50	$144.50
7 purchase totals =	$1,047.08		$1,141.5418	$1,141.54	$1,141.55	$1,141.60