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	$190.74	4.702%	$199.7086	$199.71	$199.70	$199.70
Purchase #2	$226.58	5.362%	$238.7292	$238.73	$238.75	$238.70
Purchase #3	$236.48	3.766%	$245.3858	$245.39	$245.40	$245.40
Purchase #4	$161.98	3.382%	$167.4582	$167.46	$167.45	$167.50
Purchase #5	$93.89	11.859%	$105.0244	$105.02	$105.00	$105.00
Purchase #6	$74.35	5.785%	$78.6511	$78.65	$78.65	$78.70
Purchase #7	$105.65	6.653%	$112.6789	$112.68	$112.70	$112.70
7 purchase totals =	$1,089.67		$1,147.6362	$1,147.64	$1,147.65	$1,147.70