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	$167.76	4.548%	$175.3897	$175.39	$175.40	$175.40
Purchase #2	$100.31	4.402%	$104.7256	$104.73	$104.75	$104.70
Purchase #3	$237.61	9.228%	$259.5367	$259.54	$259.55	$259.50
Purchase #4	$103.66	10.653%	$114.7029	$114.70	$114.70	$114.70
Purchase #5	$90.64	5.347%	$95.4865	$95.49	$95.50	$95.50
Purchase #6	$158.61	4.738%	$166.1249	$166.12	$166.10	$166.10
Purchase #7	$150.48	5.307%	$158.466	$158.47	$158.45	$158.50
7 purchase totals =	$1,009.07		$1,074.4323	$1,074.44	$1,074.45	$1,074.40