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	$112.81	3.401%	$116.6467	$116.65	$116.65	$116.60
Purchase #2	$6.86	4.489%	$7.1679	$7.17	$7.15	$7.20
Purchase #3	$88.66	3.144%	$91.4475	$91.45	$91.45	$91.40
Purchase #4	$68.39	6.129%	$72.5816	$72.58	$72.60	$72.60
Purchase #5	$54.36	12.655%	$61.2393	$61.24	$61.25	$61.20
Purchase #6	$118.29	5.531%	$124.8326	$124.83	$124.85	$124.80
Purchase #7	$53.96	7.630%	$58.0771	$58.08	$58.10	$58.10
7 purchase totals =	$503.33		$531.9927	$532.00	$532.05	$531.90