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	$59.50	4.611%	$62.2435	$62.24	$62.25	$62.20
Purchase #2	$247.37	3.638%	$256.3693	$256.37	$256.35	$256.40
Purchase #3	$137.69	6.429%	$146.5421	$146.54	$146.55	$146.50
Purchase #4	$139.94	13.820%	$159.2797	$159.28	$159.30	$159.30
Purchase #5	$53.37	8.301%	$57.8002	$57.80	$57.80	$57.80
Purchase #6	$157.35	10.873%	$174.4587	$174.46	$174.45	$174.50
Purchase #7	$173.56	13.228%	$196.5185	$196.52	$196.50	$196.50
7 purchase totals =	$968.78		$1,053.2120	$1,053.21	$1,053.20	$1,053.20