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	$152.96	10.374%	$168.8281	$168.83	$168.85	$168.80
Purchase #2	$24.72	10.713%	$27.3683	$27.37	$27.35	$27.40
Purchase #3	$184.34	4.214%	$192.1081	$192.11	$192.10	$192.10
Purchase #4	$195.31	10.470%	$215.759	$215.76	$215.75	$215.80
Purchase #5	$140.74	5.362%	$148.2865	$148.29	$148.30	$148.30
Purchase #6	$181.40	9.697%	$198.9904	$198.99	$199.00	$199.00
Purchase #7	$121.96	10.320%	$134.5463	$134.55	$134.55	$134.50
7 purchase totals =	$1,001.43		$1,085.8867	$1,085.90	$1,085.90	$1,085.90