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	$200.42	7.403%	$215.2571	$215.26	$215.25	$215.30
Purchase #2	$231.99	7.573%	$249.5586	$249.56	$249.55	$249.60
Purchase #3	$85.35	3.614%	$88.4345	$88.43	$88.45	$88.40
Purchase #4	$228.81	5.460%	$241.303	$241.30	$241.30	$241.30
Purchase #5	$58.36	9.139%	$63.6935	$63.69	$63.70	$63.70
Purchase #6	$41.33	6.125%	$43.8615	$43.86	$43.85	$43.90
Purchase #7	$127.43	9.756%	$139.8621	$139.86	$139.85	$139.90
7 purchase totals =	$973.69		$1,041.9703	$1,041.96	$1,041.95	$1,042.10