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	$119.94	4.440%	$125.2653	$125.27	$125.25	$125.30
Purchase #2	$72.68	13.458%	$82.4613	$82.46	$82.45	$82.50
Purchase #3	$162.78	3.425%	$168.3552	$168.36	$168.35	$168.40
Purchase #4	$52.75	12.348%	$59.2636	$59.26	$59.25	$59.30
Purchase #5	$42.39	6.524%	$45.1555	$45.16	$45.15	$45.20
Purchase #6	$63.60	5.595%	$67.1584	$67.16	$67.15	$67.20
Purchase #7	$38.91	11.734%	$43.4757	$43.48	$43.50	$43.50
7 purchase totals =	$553.05		$591.1350	$591.15	$591.10	$591.40