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	$150.83	4.825%	$158.1075	$158.11	$158.10	$158.10
Purchase #2	$137.96	8.803%	$150.1046	$150.10	$150.10	$150.10
Purchase #3	$11.54	6.698%	$12.3129	$12.31	$12.30	$12.30
Purchase #4	$145.93	8.746%	$158.693	$158.69	$158.70	$158.70
Purchase #5	$230.31	13.662%	$261.775	$261.78	$261.80	$261.80
Purchase #6	$91.57	4.133%	$95.3546	$95.35	$95.35	$95.40
Purchase #7	$228.81	5.143%	$240.5777	$240.58	$240.60	$240.60
7 purchase totals =	$996.95		$1,076.9253	$1,076.92	$1,076.95	$1,077.00