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	$213.64	4.225%	$222.6663	$222.67	$222.65	$222.70
Purchase #2	$142.50	11.392%	$158.7336	$158.73	$158.75	$158.70
Purchase #3	$170.66	8.573%	$185.2907	$185.29	$185.30	$185.30
Purchase #4	$232.61	3.514%	$240.7839	$240.78	$240.80	$240.80
Purchase #5	$31.85	5.696%	$33.6642	$33.66	$33.65	$33.70
Purchase #6	$135.54	13.590%	$153.9599	$153.96	$153.95	$154.00
Purchase #7	$144.93	11.808%	$162.0433	$162.04	$162.05	$162.00
7 purchase totals =	$1,071.73		$1,157.1419	$1,157.13	$1,157.15	$1,157.20