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	$162.98	5.493%	$171.9325	$171.93	$171.95	$171.90
Purchase #2	$214.97	12.769%	$242.4195	$242.42	$242.40	$242.40
Purchase #3	$188.47	6.171%	$200.1005	$200.10	$200.10	$200.10
Purchase #4	$75.75	5.826%	$80.1632	$80.16	$80.15	$80.20
Purchase #5	$22.69	7.131%	$24.308	$24.31	$24.30	$24.30
Purchase #6	$194.51	12.376%	$218.5826	$218.58	$218.60	$218.60
Purchase #7	$145.97	8.529%	$158.4198	$158.42	$158.40	$158.40
7 purchase totals =	$1,005.34		$1,095.9261	$1,095.92	$1,095.90	$1,095.90