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	$168.60	6.363%	$179.328	$179.33	$179.35	$179.30
Purchase #2	$168.55	7.839%	$181.7626	$181.76	$181.75	$181.80
Purchase #3	$42.86	5.210%	$45.093	$45.09	$45.10	$45.10
Purchase #4	$181.90	5.322%	$191.5807	$191.58	$191.60	$191.60
Purchase #5	$241.41	12.399%	$271.3424	$271.34	$271.35	$271.30
Purchase #6	$17.59	7.145%	$18.8468	$18.85	$18.85	$18.80
Purchase #7	$135.54	9.229%	$148.049	$148.05	$148.05	$148.00
7 purchase totals =	$956.45		$1,036.0025	$1,036.00	$1,036.05	$1,035.90