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	$211.38	3.872%	$219.5646	$219.56	$219.55	$219.60
Purchase #2	$63.93	10.156%	$70.4227	$70.42	$70.40	$70.40
Purchase #3	$90.46	13.522%	$102.692	$102.69	$102.70	$102.70
Purchase #4	$164.90	12.337%	$185.2437	$185.24	$185.25	$185.20
Purchase #5	$188.67	12.622%	$212.4839	$212.48	$212.50	$212.50
Purchase #6	$75.38	4.253%	$78.5859	$78.59	$78.60	$78.60
Purchase #7	$136.61	13.631%	$155.2313	$155.23	$155.25	$155.20
7 purchase totals =	$931.33		$1,024.2241	$1,024.21	$1,024.25	$1,024.20