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	$59.76	3.800%	$62.0309	$62.03	$62.05	$62.00
Purchase #2	$242.80	5.579%	$256.3458	$256.35	$256.35	$256.30
Purchase #3	$228.76	7.160%	$245.1392	$245.14	$245.15	$245.10
Purchase #4	$180.61	6.255%	$191.9072	$191.91	$191.90	$191.90
Purchase #5	$75.90	8.441%	$82.3067	$82.31	$82.30	$82.30
Purchase #6	$37.35	10.619%	$41.3162	$41.32	$41.30	$41.30
Purchase #7	$219.78	3.270%	$226.9668	$226.97	$226.95	$227.00
7 purchase totals =	$1,044.96		$1,106.0128	$1,106.03	$1,106.00	$1,105.90