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	$163.45	13.587%	$185.658	$185.66	$185.65	$185.70
Purchase #2	$72.80	4.310%	$75.9377	$75.94	$75.95	$75.90
Purchase #3	$121.81	4.459%	$127.2415	$127.24	$127.25	$127.20
Purchase #4	$199.83	9.221%	$218.2563	$218.26	$218.25	$218.30
Purchase #5	$51.25	8.626%	$55.6708	$55.67	$55.65	$55.70
Purchase #6	$219.72	4.785%	$230.2336	$230.23	$230.25	$230.20
Purchase #7	$123.82	6.196%	$131.4919	$131.49	$131.50	$131.50
7 purchase totals =	$952.68		$1,024.4898	$1,024.49	$1,024.50	$1,024.50