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	$185.95	5.540%	$196.2516	$196.25	$196.25	$196.30
Purchase #2	$209.90	4.301%	$218.9278	$218.93	$218.95	$218.90
Purchase #3	$238.49	5.654%	$251.9742	$251.97	$251.95	$252.00
Purchase #4	$178.51	10.762%	$197.7212	$197.72	$197.70	$197.70
Purchase #5	$79.34	9.359%	$86.7654	$86.77	$86.75	$86.80
Purchase #6	$99.28	4.173%	$103.423	$103.42	$103.40	$103.40
Purchase #7	$51.69	10.181%	$56.9526	$56.95	$56.95	$57.00
7 purchase totals =	$1,043.16		$1,112.0158	$1,112.01	$1,111.95	$1,112.10