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	$118.54	7.524%	$127.4589	$127.46	$127.45	$127.50
Purchase #2	$180.66	3.727%	$187.3932	$187.39	$187.40	$187.40
Purchase #3	$202.44	6.405%	$215.4063	$215.41	$215.40	$215.40
Purchase #4	$64.28	6.387%	$68.3856	$68.39	$68.40	$68.40
Purchase #5	$171.87	10.158%	$189.3286	$189.33	$189.35	$189.30
Purchase #6	$66.47	8.747%	$72.2841	$72.28	$72.30	$72.30
Purchase #7	$143.42	8.545%	$155.6752	$155.68	$155.70	$155.70
7 purchase totals =	$947.68		$1,015.9319	$1,015.94	$1,016.00	$1,016.00