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	$53.67	11.499%	$59.8415	$59.84	$59.85	$59.80
Purchase #2	$91.51	13.531%	$103.8922	$103.89	$103.90	$103.90
Purchase #3	$5.56	6.116%	$5.9	$5.90	$5.90	$5.90
Purchase #4	$172.27	3.166%	$177.7241	$177.72	$177.70	$177.70
Purchase #5	$131.72	9.601%	$144.3664	$144.37	$144.35	$144.40
Purchase #6	$214.92	4.688%	$224.9954	$225.00	$225.00	$225.00
Purchase #7	$146.56	6.449%	$156.0117	$156.01	$156.00	$156.00
7 purchase totals =	$816.21		$872.7313	$872.73	$872.70	$872.70