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	$78.74	10.807%	$87.2494	$87.25	$87.25	$87.20
Purchase #2	$54.92	4.794%	$57.5529	$57.55	$57.55	$57.60
Purchase #3	$39.83	7.683%	$42.8901	$42.89	$42.90	$42.90
Purchase #4	$189.42	12.422%	$212.9498	$212.95	$212.95	$212.90
Purchase #5	$199.74	7.181%	$214.0833	$214.08	$214.10	$214.10
Purchase #6	$233.61	3.162%	$240.9967	$241.00	$241.00	$241.00
Purchase #7	$147.33	12.402%	$165.6019	$165.60	$165.60	$165.60
7 purchase totals =	$943.59		$1,021.3241	$1,021.32	$1,021.35	$1,021.30