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	$184.55	3.756%	$191.4817	$191.48	$191.50	$191.50
Purchase #2	$55.64	10.542%	$61.5056	$61.51	$61.50	$61.50
Purchase #3	$78.29	9.755%	$85.9272	$85.93	$85.95	$85.90
Purchase #4	$185.85	11.239%	$206.7377	$206.74	$206.75	$206.70
Purchase #5	$195.92	12.270%	$219.9594	$219.96	$219.95	$220.00
Purchase #6	$175.37	3.121%	$180.8433	$180.84	$180.85	$180.80
Purchase #7	$106.85	9.103%	$116.5766	$116.58	$116.60	$116.60
7 purchase totals =	$982.47		$1,063.0315	$1,063.04	$1,063.10	$1,063.00