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	$187.89	4.771%	$196.8542	$196.85	$196.85	$196.90
Purchase #2	$205.52	3.325%	$212.3535	$212.35	$212.35	$212.40
Purchase #3	$47.98	9.270%	$52.4277	$52.43	$52.45	$52.40
Purchase #4	$164.78	12.417%	$185.2407	$185.24	$185.25	$185.20
Purchase #5	$125.35	7.570%	$134.839	$134.84	$134.85	$134.80
Purchase #6	$197.43	12.737%	$222.5767	$222.58	$222.60	$222.60
Purchase #7	$70.39	3.474%	$72.8353	$72.84	$72.85	$72.80
7 purchase totals =	$999.34		$1,077.1271	$1,077.13	$1,077.20	$1,077.10