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	$233.27	5.385%	$245.8316	$245.83	$245.85	$245.80
Purchase #2	$240.43	13.235%	$272.2509	$272.25	$272.25	$272.30
Purchase #3	$62.48	11.801%	$69.8533	$69.85	$69.85	$69.90
Purchase #4	$52.71	13.232%	$59.6846	$59.68	$59.70	$59.70
Purchase #5	$92.32	11.840%	$103.2507	$103.25	$103.25	$103.30
Purchase #6	$136.97	8.718%	$148.911	$148.91	$148.90	$148.90
Purchase #7	$113.46	11.736%	$126.7757	$126.78	$126.80	$126.80
7 purchase totals =	$931.64		$1,026.5578	$1,026.55	$1,026.60	$1,026.70