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	$105.43	11.243%	$117.2835	$117.28	$117.30	$117.30
Purchase #2	$232.86	11.505%	$259.6505	$259.65	$259.65	$259.70
Purchase #3	$117.91	11.475%	$131.4402	$131.44	$131.45	$131.40
Purchase #4	$60.50	13.796%	$68.8466	$68.85	$68.85	$68.80
Purchase #5	$179.97	5.788%	$190.3867	$190.39	$190.40	$190.40
Purchase #6	$221.45	13.142%	$250.553	$250.55	$250.55	$250.60
Purchase #7	$143.79	4.857%	$150.7739	$150.77	$150.75	$150.80
7 purchase totals =	$1,061.91		$1,168.9344	$1,168.93	$1,168.95	$1,169.00