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	$200.62	6.144%	$212.9461	$212.95	$212.95	$212.90
Purchase #2	$185.59	5.523%	$195.8401	$195.84	$195.85	$195.80
Purchase #3	$54.33	9.167%	$59.3104	$59.31	$59.30	$59.30
Purchase #4	$80.59	5.546%	$85.0595	$85.06	$85.05	$85.10
Purchase #5	$239.98	3.842%	$249.2	$249.20	$249.20	$249.20
Purchase #6	$163.96	6.208%	$174.1386	$174.14	$174.15	$174.10
Purchase #7	$86.71	4.361%	$90.4914	$90.49	$90.50	$90.50
7 purchase totals =	$1,011.78		$1,066.9861	$1,066.99	$1,067.00	$1,066.90