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	$184.45	4.143%	$192.0918	$192.09	$192.10	$192.10
Purchase #2	$148.97	3.301%	$153.8875	$153.89	$153.90	$153.90
Purchase #3	$49.88	4.831%	$52.2897	$52.29	$52.30	$52.30
Purchase #4	$127.30	10.418%	$140.5621	$140.56	$140.55	$140.60
Purchase #5	$57.93	13.173%	$65.5611	$65.56	$65.55	$65.60
Purchase #6	$150.84	11.537%	$168.2424	$168.24	$168.25	$168.20
Purchase #7	$97.62	12.213%	$109.5423	$109.54	$109.55	$109.50
7 purchase totals =	$816.99		$882.1769	$882.17	$882.20	$882.20