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	$179.93	11.606%	$200.8127	$200.81	$200.80	$200.80
Purchase #2	$19.81	3.529%	$20.5091	$20.51	$20.50	$20.50
Purchase #3	$44.45	3.658%	$46.076	$46.08	$46.10	$46.10
Purchase #4	$200.79	6.324%	$213.488	$213.49	$213.50	$213.50
Purchase #5	$217.70	13.725%	$247.5793	$247.58	$247.60	$247.60
Purchase #6	$168.27	12.742%	$189.711	$189.71	$189.70	$189.70
Purchase #7	$142.39	4.838%	$149.2788	$149.28	$149.30	$149.30
7 purchase totals =	$973.34		$1,067.4549	$1,067.46	$1,067.50	$1,067.50