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	$87.33	7.546%	$93.9199	$93.92	$93.90	$93.90
Purchase #2	$242.76	5.497%	$256.1045	$256.10	$256.10	$256.10
Purchase #3	$11.30	5.315%	$11.9006	$11.90	$11.90	$11.90
Purchase #4	$14.57	13.122%	$16.4819	$16.48	$16.50	$16.50
Purchase #5	$159.69	12.599%	$179.8093	$179.81	$179.80	$179.80
Purchase #6	$73.27	6.805%	$78.256	$78.26	$78.25	$78.30
Purchase #7	$116.28	6.196%	$123.4847	$123.48	$123.50	$123.50
7 purchase totals =	$705.20		$759.9569	$759.95	$759.95	$760.00