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	$214.42	13.454%	$243.2681	$243.27	$243.25	$243.30
Purchase #2	$144.47	12.551%	$162.6024	$162.60	$162.60	$162.60
Purchase #3	$15.42	7.413%	$16.5631	$16.56	$16.55	$16.60
Purchase #4	$80.39	3.383%	$83.1096	$83.11	$83.10	$83.10
Purchase #5	$242.86	12.769%	$273.8708	$273.87	$273.85	$273.90
Purchase #6	$236.50	3.635%	$245.0968	$245.10	$245.10	$245.10
Purchase #7	$65.31	6.465%	$69.5323	$69.53	$69.55	$69.50
7 purchase totals =	$999.37		$1,094.0431	$1,094.04	$1,094.00	$1,094.10