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	$196.91	4.356%	$205.4874	$205.49	$205.50	$205.50
Purchase #2	$113.31	5.268%	$119.2792	$119.28	$119.30	$119.30
Purchase #3	$87.90	5.325%	$92.5807	$92.58	$92.60	$92.60
Purchase #4	$57.33	13.319%	$64.9658	$64.97	$64.95	$65.00
Purchase #5	$137.61	11.118%	$152.9095	$152.91	$152.90	$152.90
Purchase #6	$76.64	12.790%	$86.4423	$86.44	$86.45	$86.40
Purchase #7	$96.43	4.550%	$100.8176	$100.82	$100.80	$100.80
7 purchase totals =	$766.13		$822.4825	$822.49	$822.50	$822.50