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	$192.29	11.594%	$214.5841	$214.58	$214.60	$214.60
Purchase #2	$92.98	10.248%	$102.5086	$102.51	$102.50	$102.50
Purchase #3	$144.62	8.317%	$156.648	$156.65	$156.65	$156.60
Purchase #4	$62.58	13.726%	$71.1697	$71.17	$71.15	$71.20
Purchase #5	$167.46	7.365%	$179.7934	$179.79	$179.80	$179.80
Purchase #6	$169.61	8.560%	$184.1286	$184.13	$184.15	$184.10
Purchase #7	$197.33	10.814%	$218.6693	$218.67	$218.65	$218.70
7 purchase totals =	$1,026.87		$1,127.5017	$1,127.50	$1,127.50	$1,127.50