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	$110.96	3.312%	$114.635	$114.64	$114.65	$114.60
Purchase #2	$32.38	3.533%	$33.524	$33.52	$33.50	$33.50
Purchase #3	$242.27	13.850%	$275.8244	$275.82	$275.80	$275.80
Purchase #4	$14.26	3.728%	$14.7916	$14.79	$14.80	$14.80
Purchase #5	$176.40	8.243%	$190.9407	$190.94	$190.95	$190.90
Purchase #6	$33.79	10.329%	$37.2802	$37.28	$37.30	$37.30
Purchase #7	$93.77	7.690%	$100.9809	$100.98	$101.00	$101.00
7 purchase totals =	$703.83		$767.9768	$767.97	$768.00	$767.90