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	$164.65	4.301%	$171.7316	$171.73	$171.75	$171.70
Purchase #2	$89.70	7.850%	$96.7415	$96.74	$96.75	$96.70
Purchase #3	$52.78	12.479%	$59.3664	$59.37	$59.35	$59.40
Purchase #4	$32.64	10.697%	$36.1315	$36.13	$36.15	$36.10
Purchase #5	$224.41	10.732%	$248.4937	$248.49	$248.50	$248.50
Purchase #6	$65.77	3.253%	$67.9095	$67.91	$67.90	$67.90
Purchase #7	$241.98	10.225%	$266.7225	$266.72	$266.70	$266.70
7 purchase totals =	$871.93		$947.0967	$947.09	$947.10	$947.00