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	$175.54	8.299%	$190.1081	$190.11	$190.10	$190.10
Purchase #2	$34.55	8.162%	$37.37	$37.37	$37.35	$37.40
Purchase #3	$113.81	13.137%	$128.7612	$128.76	$128.75	$128.80
Purchase #4	$100.27	13.280%	$113.5859	$113.59	$113.60	$113.60
Purchase #5	$216.74	6.841%	$231.5672	$231.57	$231.55	$231.60
Purchase #6	$84.35	13.396%	$95.6495	$95.65	$95.65	$95.60
Purchase #7	$217.29	3.321%	$224.5062	$224.51	$224.50	$224.50
7 purchase totals =	$942.55		$1,021.5481	$1,021.56	$1,021.50	$1,021.60