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	$87.83	5.233%	$92.4261	$92.43	$92.45	$92.40
Purchase #2	$189.83	12.388%	$213.3461	$213.35	$213.35	$213.30
Purchase #3	$97.47	10.705%	$107.9042	$107.90	$107.90	$107.90
Purchase #4	$105.89	11.674%	$118.2516	$118.25	$118.25	$118.30
Purchase #5	$206.93	11.778%	$231.3022	$231.30	$231.30	$231.30
Purchase #6	$59.73	5.310%	$62.9017	$62.90	$62.90	$62.90
Purchase #7	$218.28	7.850%	$235.415	$235.42	$235.40	$235.40
7 purchase totals =	$965.96		$1,061.5469	$1,061.55	$1,061.55	$1,061.50