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	$112.59	3.234%	$116.2312	$116.23	$116.25	$116.20
Purchase #2	$46.96	3.488%	$48.598	$48.60	$48.60	$48.60
Purchase #3	$178.35	9.490%	$195.2754	$195.28	$195.30	$195.30
Purchase #4	$89.68	12.570%	$100.9528	$100.95	$100.95	$101.00
Purchase #5	$78.36	8.607%	$85.1044	$85.10	$85.10	$85.10
Purchase #6	$221.88	9.547%	$243.0629	$243.06	$243.05	$243.10
Purchase #7	$130.64	10.734%	$144.6629	$144.66	$144.65	$144.70
7 purchase totals =	$858.46		$933.8876	$933.88	$933.90	$934.00