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	$118.85	7.539%	$127.8101	$127.81	$127.80	$127.80
Purchase #2	$7.44	6.644%	$7.9343	$7.93	$7.95	$7.90
Purchase #3	$76.71	11.436%	$85.4826	$85.48	$85.50	$85.50
Purchase #4	$48.90	8.211%	$52.9152	$52.92	$52.90	$52.90
Purchase #5	$224.54	7.388%	$241.129	$241.13	$241.15	$241.10
Purchase #6	$84.57	13.155%	$95.6952	$95.70	$95.70	$95.70
Purchase #7	$158.76	3.544%	$164.3865	$164.39	$164.40	$164.40
7 purchase totals =	$719.77		$775.3529	$775.36	$775.40	$775.30