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	$157.60	10.554%	$174.2331	$174.23	$174.25	$174.20
Purchase #2	$81.82	9.184%	$89.3343	$89.33	$89.35	$89.30
Purchase #3	$240.79	6.719%	$256.9687	$256.97	$256.95	$257.00
Purchase #4	$212.31	13.721%	$241.4411	$241.44	$241.45	$241.40
Purchase #5	$48.25	6.555%	$51.4128	$51.41	$51.40	$51.40
Purchase #6	$140.42	3.375%	$145.1592	$145.16	$145.15	$145.20
Purchase #7	$85.26	10.805%	$94.4723	$94.47	$94.45	$94.50
7 purchase totals =	$966.45		$1,053.0215	$1,053.01	$1,053.00	$1,053.00