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	$32.88	7.143%	$35.2286	$35.23	$35.25	$35.20
Purchase #2	$76.66	12.125%	$85.955	$85.96	$85.95	$86.00
Purchase #3	$36.96	11.671%	$41.2736	$41.27	$41.25	$41.30
Purchase #4	$40.93	12.658%	$46.1109	$46.11	$46.10	$46.10
Purchase #5	$189.90	8.356%	$205.768	$205.77	$205.75	$205.80
Purchase #6	$140.57	10.470%	$155.2877	$155.29	$155.30	$155.30
Purchase #7	$149.61	3.537%	$154.9017	$154.90	$154.90	$154.90
7 purchase totals =	$667.51		$724.5255	$724.53	$724.50	$724.60