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	$168.61	13.844%	$191.9524	$191.95	$191.95	$192.00
Purchase #2	$82.89	11.642%	$92.5401	$92.54	$92.55	$92.50
Purchase #3	$244.79	4.541%	$255.9059	$255.91	$255.90	$255.90
Purchase #4	$158.90	11.345%	$176.9272	$176.93	$176.95	$176.90
Purchase #5	$195.63	11.332%	$217.7988	$217.80	$217.80	$217.80
Purchase #6	$151.86	5.309%	$159.9222	$159.92	$159.90	$159.90
Purchase #7	$103.33	9.778%	$113.4336	$113.43	$113.45	$113.40
7 purchase totals =	$1,106.01		$1,208.4802	$1,208.48	$1,208.50	$1,208.40