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	$213.94	12.851%	$241.4334	$241.43	$241.45	$241.40
Purchase #2	$139.51	11.427%	$155.4518	$155.45	$155.45	$155.50
Purchase #3	$209.81	8.454%	$227.5473	$227.55	$227.55	$227.50
Purchase #4	$212.52	10.624%	$235.0981	$235.10	$235.10	$235.10
Purchase #5	$144.56	8.355%	$156.638	$156.64	$156.65	$156.60
Purchase #6	$62.86	11.650%	$70.1832	$70.18	$70.20	$70.20
Purchase #7	$53.72	6.800%	$57.373	$57.37	$57.35	$57.40
7 purchase totals =	$1,036.92		$1,143.7248	$1,143.72	$1,143.75	$1,143.70