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	$219.41	11.851%	$245.4123	$245.41	$245.40	$245.40
Purchase #2	$230.28	10.737%	$255.0052	$255.01	$255.00	$255.00
Purchase #3	$150.82	11.525%	$168.202	$168.20	$168.20	$168.20
Purchase #4	$194.31	8.321%	$210.4785	$210.48	$210.50	$210.50
Purchase #5	$37.36	11.240%	$41.5593	$41.56	$41.55	$41.60
Purchase #6	$67.55	3.214%	$69.7211	$69.72	$69.70	$69.70
Purchase #7	$44.59	4.112%	$46.4235	$46.42	$46.40	$46.40
7 purchase totals =	$944.32		$1,036.8019	$1,036.80	$1,036.75	$1,036.80