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	$176.96	7.542%	$190.3063	$190.31	$190.30	$190.30
Purchase #2	$106.95	5.868%	$113.2258	$113.23	$113.25	$113.20
Purchase #3	$67.26	5.719%	$71.1066	$71.11	$71.10	$71.10
Purchase #4	$91.73	8.803%	$99.805	$99.81	$99.80	$99.80
Purchase #5	$97.29	8.797%	$105.8486	$105.85	$105.85	$105.80
Purchase #6	$7.56	5.492%	$7.9752	$7.98	$8.00	$8.00
Purchase #7	$131.55	5.691%	$139.0365	$139.04	$139.05	$139.00
7 purchase totals =	$679.30		$727.3040	$727.33	$727.35	$727.20