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	$176.81	11.742%	$197.571	$197.57	$197.55	$197.60
Purchase #2	$29.44	5.670%	$31.1092	$31.11	$31.10	$31.10
Purchase #3	$161.46	3.296%	$166.7817	$166.78	$166.80	$166.80
Purchase #4	$148.28	7.532%	$159.4484	$159.45	$159.45	$159.40
Purchase #5	$137.81	4.605%	$144.1562	$144.16	$144.15	$144.20
Purchase #6	$158.47	6.511%	$168.788	$168.79	$168.80	$168.80
Purchase #7	$244.56	4.700%	$256.0543	$256.05	$256.05	$256.10
7 purchase totals =	$1,056.83		$1,123.9088	$1,123.91	$1,123.90	$1,124.00