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	$90.57	4.860%	$94.9717	$94.97	$94.95	$95.00
Purchase #2	$37.56	10.265%	$41.4155	$41.42	$41.40	$41.40
Purchase #3	$112.83	10.652%	$124.8487	$124.85	$124.85	$124.80
Purchase #4	$71.40	11.565%	$79.6574	$79.66	$79.65	$79.70
Purchase #5	$38.60	7.645%	$41.551	$41.55	$41.55	$41.60
Purchase #6	$171.43	8.434%	$185.8884	$185.89	$185.90	$185.90
Purchase #7	$123.56	10.539%	$136.582	$136.58	$136.60	$136.60
7 purchase totals =	$645.95		$704.9147	$704.92	$704.90	$705.00