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	$82.63	5.372%	$87.0689	$87.07	$87.05	$87.10
Purchase #2	$131.99	3.136%	$136.1292	$136.13	$136.15	$136.10
Purchase #3	$95.29	4.716%	$99.7839	$99.78	$99.80	$99.80
Purchase #4	$232.87	13.314%	$263.8743	$263.87	$263.85	$263.90
Purchase #5	$148.76	3.771%	$154.3697	$154.37	$154.35	$154.40
Purchase #6	$154.61	8.168%	$167.2385	$167.24	$167.25	$167.20
Purchase #7	$111.74	4.179%	$116.4096	$116.41	$116.40	$116.40
7 purchase totals =	$957.89		$1,024.8741	$1,024.87	$1,024.85	$1,024.90