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	$217.86	7.676%	$234.5829	$234.58	$234.60	$234.60
Purchase #2	$27.32	13.818%	$31.0951	$31.10	$31.10	$31.10
Purchase #3	$62.49	10.473%	$69.0346	$69.03	$69.05	$69.00
Purchase #4	$154.44	6.788%	$164.9234	$164.92	$164.90	$164.90
Purchase #5	$79.72	3.105%	$82.1953	$82.20	$82.20	$82.20
Purchase #6	$163.78	13.252%	$185.4841	$185.48	$185.50	$185.50
Purchase #7	$246.77	9.786%	$270.9189	$270.92	$270.90	$270.90
7 purchase totals =	$952.38		$1,038.2343	$1,038.23	$1,038.25	$1,038.20