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	$47.62	10.541%	$52.6396	$52.64	$52.65	$52.60
Purchase #2	$95.36	10.512%	$105.3842	$105.38	$105.40	$105.40
Purchase #3	$65.26	10.692%	$72.2376	$72.24	$72.25	$72.20
Purchase #4	$117.58	7.368%	$126.2433	$126.24	$126.25	$126.20
Purchase #5	$191.49	9.603%	$209.8788	$209.88	$209.90	$209.90
Purchase #6	$89.36	10.762%	$98.9769	$98.98	$99.00	$99.00
Purchase #7	$33.55	10.682%	$37.1338	$37.13	$37.15	$37.10
7 purchase totals =	$640.22		$702.4942	$702.49	$702.60	$702.40