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	$183.35	4.704%	$191.9748	$191.97	$191.95	$192.00
Purchase #2	$156.29	10.212%	$172.2503	$172.25	$172.25	$172.30
Purchase #3	$50.74	4.527%	$53.037	$53.04	$53.05	$53.00
Purchase #4	$135.32	3.627%	$140.2281	$140.23	$140.25	$140.20
Purchase #5	$78.58	5.456%	$82.8673	$82.87	$82.85	$82.90
Purchase #6	$170.53	5.695%	$180.2417	$180.24	$180.25	$180.20
Purchase #7	$51.83	5.411%	$54.6345	$54.63	$54.65	$54.60
7 purchase totals =	$826.64		$875.2337	$875.23	$875.25	$875.20