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	$73.60	6.197%	$78.161	$78.16	$78.15	$78.20
Purchase #2	$42.43	3.694%	$43.9974	$44.00	$44.00	$44.00
Purchase #3	$198.65	10.119%	$218.7514	$218.75	$218.75	$218.80
Purchase #4	$219.84	9.830%	$241.4503	$241.45	$241.45	$241.50
Purchase #5	$233.64	3.524%	$241.8735	$241.87	$241.85	$241.90
Purchase #6	$131.80	11.299%	$146.6921	$146.69	$146.70	$146.70
Purchase #7	$199.87	5.807%	$211.4765	$211.48	$211.50	$211.50
7 purchase totals =	$1,099.83		$1,182.4022	$1,182.40	$1,182.40	$1,182.60