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	$187.26	4.735%	$196.1268	$196.13	$196.15	$196.10
Purchase #2	$61.72	5.469%	$65.0955	$65.10	$65.10	$65.10
Purchase #3	$125.69	10.816%	$139.2846	$139.28	$139.30	$139.30
Purchase #4	$50.26	12.320%	$56.452	$56.45	$56.45	$56.50
Purchase #5	$102.61	8.353%	$111.181	$111.18	$111.20	$111.20
Purchase #6	$94.26	5.234%	$99.1936	$99.19	$99.20	$99.20
Purchase #7	$133.58	8.447%	$144.8635	$144.86	$144.85	$144.90
7 purchase totals =	$755.38		$812.1970	$812.19	$812.25	$812.30