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	$119.56	3.684%	$123.9646	$123.96	$123.95	$124.00
Purchase #2	$169.31	8.229%	$183.2425	$183.24	$183.25	$183.20
Purchase #3	$94.93	6.309%	$100.9191	$100.92	$100.90	$100.90
Purchase #4	$176.66	13.146%	$199.8837	$199.88	$199.90	$199.90
Purchase #5	$52.50	6.448%	$55.8852	$55.89	$55.90	$55.90
Purchase #6	$168.79	6.323%	$179.4626	$179.46	$179.45	$179.50
Purchase #7	$191.96	5.576%	$202.6637	$202.66	$202.65	$202.70
7 purchase totals =	$973.71		$1,046.0214	$1,046.01	$1,046.00	$1,046.10