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	$228.28	5.673%	$241.2303	$241.23	$241.25	$241.20
Purchase #2	$156.61	11.576%	$174.7392	$174.74	$174.75	$174.70
Purchase #3	$40.60	7.232%	$43.5362	$43.54	$43.55	$43.50
Purchase #4	$208.96	6.567%	$222.6824	$222.68	$222.70	$222.70
Purchase #5	$54.83	12.174%	$61.505	$61.51	$61.50	$61.50
Purchase #6	$201.67	9.787%	$221.4074	$221.41	$221.40	$221.40
Purchase #7	$43.85	11.661%	$48.9633	$48.96	$48.95	$49.00
7 purchase totals =	$934.80		$1,014.0638	$1,014.07	$1,014.10	$1,014.00