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	$185.57	7.852%	$200.141	$200.14	$200.15	$200.10
Purchase #2	$82.54	3.335%	$85.2927	$85.29	$85.30	$85.30
Purchase #3	$250.87	6.298%	$266.6698	$266.67	$266.65	$266.70
Purchase #4	$205.72	8.312%	$222.8194	$222.82	$222.80	$222.80
Purchase #5	$64.50	9.869%	$70.8655	$70.87	$70.85	$70.90
Purchase #6	$112.29	13.583%	$127.5424	$127.54	$127.55	$127.50
Purchase #7	$212.54	7.277%	$228.0065	$228.01	$228.00	$228.00
7 purchase totals =	$1,114.03		$1,201.3373	$1,201.34	$1,201.30	$1,201.30