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	$182.79	9.719%	$200.5554	$200.56	$200.55	$200.60
Purchase #2	$86.25	6.274%	$91.6613	$91.66	$91.65	$91.70
Purchase #3	$53.32	4.153%	$55.5344	$55.53	$55.55	$55.50
Purchase #4	$163.61	5.830%	$173.1485	$173.15	$173.15	$173.10
Purchase #5	$105.25	8.810%	$114.5225	$114.52	$114.50	$114.50
Purchase #6	$201.66	7.468%	$216.72	$216.72	$216.70	$216.70
Purchase #7	$198.51	6.347%	$211.1094	$211.11	$211.10	$211.10
7 purchase totals =	$991.39		$1,063.2515	$1,063.25	$1,063.20	$1,063.20