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	$196.62	13.166%	$222.507	$222.51	$222.50	$222.50
Purchase #2	$242.27	4.761%	$253.8045	$253.80	$253.80	$253.80
Purchase #3	$179.63	5.853%	$190.1437	$190.14	$190.15	$190.10
Purchase #4	$129.90	11.136%	$144.3657	$144.37	$144.35	$144.40
Purchase #5	$124.95	4.401%	$130.449	$130.45	$130.45	$130.40
Purchase #6	$22.48	6.436%	$23.9268	$23.93	$23.95	$23.90
Purchase #7	$81.46	8.511%	$88.3931	$88.39	$88.40	$88.40
7 purchase totals =	$977.31		$1,053.5898	$1,053.59	$1,053.60	$1,053.50