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	$83.86	13.588%	$95.2549	$95.25	$95.25	$95.30
Purchase #2	$32.53	3.437%	$33.6481	$33.65	$33.65	$33.60
Purchase #3	$57.89	12.449%	$65.0967	$65.10	$65.10	$65.10
Purchase #4	$159.79	12.608%	$179.9363	$179.94	$179.95	$179.90
Purchase #5	$227.59	12.285%	$255.5494	$255.55	$255.55	$255.50
Purchase #6	$123.51	7.520%	$132.798	$132.80	$132.80	$132.80
Purchase #7	$184.94	11.518%	$206.2414	$206.24	$206.25	$206.20
7 purchase totals =	$870.11		$968.5248	$968.53	$968.55	$968.40