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	$226.26	7.440%	$243.0937	$243.09	$243.10	$243.10
Purchase #2	$11.29	13.538%	$12.8184	$12.82	$12.80	$12.80
Purchase #3	$5.61	13.514%	$6.3681	$6.37	$6.35	$6.40
Purchase #4	$99.40	10.309%	$109.6471	$109.65	$109.65	$109.60
Purchase #5	$94.97	4.678%	$99.4127	$99.41	$99.40	$99.40
Purchase #6	$173.93	13.110%	$196.7322	$196.73	$196.75	$196.70
Purchase #7	$103.37	11.282%	$115.0322	$115.03	$115.05	$115.00
7 purchase totals =	$714.83		$783.1044	$783.10	$783.10	$783.00