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	$209.39	4.677%	$219.1832	$219.18	$219.20	$219.20
Purchase #2	$179.83	3.189%	$185.5648	$185.56	$185.55	$185.60
Purchase #3	$211.71	5.282%	$222.8925	$222.89	$222.90	$222.90
Purchase #4	$84.83	9.262%	$92.687	$92.69	$92.70	$92.70
Purchase #5	$39.63	10.486%	$43.7856	$43.79	$43.80	$43.80
Purchase #6	$182.64	7.848%	$196.9736	$196.97	$196.95	$197.00
Purchase #7	$237.91	6.397%	$253.1291	$253.13	$253.15	$253.10
7 purchase totals =	$1,145.94		$1,214.2158	$1,214.21	$1,214.25	$1,214.30