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	$91.77	4.360%	$95.7712	$95.77	$95.75	$95.80
Purchase #2	$154.48	8.416%	$167.481	$167.48	$167.50	$167.50
Purchase #3	$233.81	10.443%	$258.2268	$258.23	$258.25	$258.20
Purchase #4	$215.55	12.145%	$241.7285	$241.73	$241.75	$241.70
Purchase #5	$81.56	4.410%	$85.1568	$85.16	$85.15	$85.20
Purchase #6	$40.75	3.696%	$42.2561	$42.26	$42.25	$42.30
Purchase #7	$73.75	3.168%	$76.0864	$76.09	$76.10	$76.10
7 purchase totals =	$891.67		$966.7068	$966.72	$966.75	$966.80