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	$98.95	10.204%	$109.0469	$109.05	$109.05	$109.00
Purchase #2	$188.67	13.496%	$214.1329	$214.13	$214.15	$214.10
Purchase #3	$196.34	6.234%	$208.5798	$208.58	$208.60	$208.60
Purchase #4	$105.83	13.764%	$120.3964	$120.40	$120.40	$120.40
Purchase #5	$157.55	13.707%	$179.1454	$179.15	$179.15	$179.10
Purchase #6	$157.60	8.684%	$171.286	$171.29	$171.30	$171.30
Purchase #7	$200.68	10.836%	$222.4257	$222.43	$222.45	$222.40
7 purchase totals =	$1,105.62		$1,225.0131	$1,225.03	$1,225.10	$1,224.90