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	$159.40	6.227%	$169.3258	$169.33	$169.35	$169.30
Purchase #2	$223.82	4.611%	$234.1403	$234.14	$234.15	$234.10
Purchase #3	$15.46	4.683%	$16.184	$16.18	$16.20	$16.20
Purchase #4	$207.48	3.517%	$214.7771	$214.78	$214.80	$214.80
Purchase #5	$241.86	9.310%	$264.3772	$264.38	$264.40	$264.40
Purchase #6	$89.87	5.129%	$94.4794	$94.48	$94.50	$94.50
Purchase #7	$90.90	13.847%	$103.4869	$103.49	$103.50	$103.50
7 purchase totals =	$1,028.79		$1,096.7707	$1,096.78	$1,096.90	$1,096.80