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	$216.45	3.194%	$223.3634	$223.36	$223.35	$223.40
Purchase #2	$56.28	13.501%	$63.8784	$63.88	$63.90	$63.90
Purchase #3	$194.57	10.121%	$214.2624	$214.26	$214.25	$214.30
Purchase #4	$124.81	12.388%	$140.2715	$140.27	$140.25	$140.30
Purchase #5	$56.48	4.557%	$59.0538	$59.05	$59.05	$59.10
Purchase #6	$177.74	3.253%	$183.5219	$183.52	$183.50	$183.50
Purchase #7	$213.43	9.581%	$233.8787	$233.88	$233.90	$233.90
7 purchase totals =	$1,039.76		$1,118.2301	$1,118.22	$1,118.20	$1,118.40