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	$174.35	5.689%	$184.2688	$184.27	$184.25	$184.30
Purchase #2	$169.43	5.667%	$179.0316	$179.03	$179.05	$179.00
Purchase #3	$119.74	13.867%	$136.3443	$136.34	$136.35	$136.30
Purchase #4	$42.92	8.606%	$46.6137	$46.61	$46.60	$46.60
Purchase #5	$218.44	5.853%	$231.2253	$231.23	$231.25	$231.20
Purchase #6	$82.42	4.120%	$85.8157	$85.82	$85.80	$85.80
Purchase #7	$84.82	8.264%	$91.8295	$91.83	$91.85	$91.80
7 purchase totals =	$892.12		$955.1289	$955.13	$955.15	$955.00