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	$197.80	3.409%	$204.543	$204.54	$204.55	$204.50
Purchase #2	$250.35	5.372%	$263.7988	$263.80	$263.80	$263.80
Purchase #3	$78.96	13.196%	$89.3796	$89.38	$89.40	$89.40
Purchase #4	$132.92	13.492%	$150.8536	$150.85	$150.85	$150.90
Purchase #5	$162.45	6.246%	$172.5966	$172.60	$172.60	$172.60
Purchase #6	$138.53	8.677%	$150.5502	$150.55	$150.55	$150.60
Purchase #7	$135.88	8.571%	$147.5263	$147.53	$147.55	$147.50
7 purchase totals =	$1,096.89		$1,179.2481	$1,179.25	$1,179.30	$1,179.30