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	$178.52	10.268%	$196.8504	$196.85	$196.85	$196.90
Purchase #2	$163.34	12.778%	$184.2116	$184.21	$184.20	$184.20
Purchase #3	$181.41	8.483%	$196.799	$196.80	$196.80	$196.80
Purchase #4	$38.78	9.572%	$42.492	$42.49	$42.50	$42.50
Purchase #5	$199.93	7.370%	$214.6648	$214.66	$214.65	$214.70
Purchase #6	$186.75	4.507%	$195.1668	$195.17	$195.15	$195.20
Purchase #7	$77.89	6.839%	$83.2169	$83.22	$83.20	$83.20
7 purchase totals =	$1,026.62		$1,113.4015	$1,113.40	$1,113.35	$1,113.50