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	$185.72	10.133%	$204.539	$204.54	$204.55	$204.50
Purchase #2	$149.37	7.850%	$161.0955	$161.10	$161.10	$161.10
Purchase #3	$167.77	10.199%	$184.8809	$184.88	$184.90	$184.90
Purchase #4	$163.72	3.126%	$168.8379	$168.84	$168.85	$168.80
Purchase #5	$38.94	7.580%	$41.8917	$41.89	$41.90	$41.90
Purchase #6	$162.89	9.853%	$178.9396	$178.94	$178.95	$178.90
Purchase #7	$94.32	12.776%	$106.3703	$106.37	$106.35	$106.40
7 purchase totals =	$962.73		$1,046.5549	$1,046.56	$1,046.60	$1,046.50