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	$92.58	3.164%	$95.5092	$95.51	$95.50	$95.50
Purchase #2	$107.98	10.309%	$119.1117	$119.11	$119.10	$119.10
Purchase #3	$141.83	9.228%	$154.9181	$154.92	$154.90	$154.90
Purchase #4	$219.56	6.712%	$234.2969	$234.30	$234.30	$234.30
Purchase #5	$231.66	13.274%	$262.4105	$262.41	$262.40	$262.40
Purchase #6	$34.32	3.510%	$35.5246	$35.52	$35.50	$35.50
Purchase #7	$159.25	9.531%	$174.4281	$174.43	$174.45	$174.40
7 purchase totals =	$987.18		$1,076.1991	$1,076.20	$1,076.15	$1,076.10