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	$223.80	5.428%	$235.9479	$235.95	$235.95	$235.90
Purchase #2	$13.32	8.632%	$14.4698	$14.47	$14.45	$14.50
Purchase #3	$121.73	12.370%	$136.788	$136.79	$136.80	$136.80
Purchase #4	$101.83	9.340%	$111.3409	$111.34	$111.35	$111.30
Purchase #5	$199.98	4.269%	$208.5171	$208.52	$208.50	$208.50
Purchase #6	$10.61	11.798%	$11.8618	$11.86	$11.85	$11.90
Purchase #7	$160.48	4.475%	$167.6615	$167.66	$167.65	$167.70
7 purchase totals =	$831.75		$886.5870	$886.59	$886.55	$886.60