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	$117.85	6.725%	$125.7754	$125.78	$125.80	$125.80
Purchase #2	$145.80	11.132%	$162.0305	$162.03	$162.05	$162.00
Purchase #3	$22.32	4.637%	$23.355	$23.36	$23.35	$23.40
Purchase #4	$113.66	8.559%	$123.3882	$123.39	$123.40	$123.40
Purchase #5	$37.25	8.723%	$40.4993	$40.50	$40.50	$40.50
Purchase #6	$147.30	3.390%	$152.2935	$152.29	$152.30	$152.30
Purchase #7	$244.71	10.530%	$270.478	$270.48	$270.50	$270.50
7 purchase totals =	$828.89		$897.8199	$897.83	$897.90	$897.90