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	$174.48	9.116%	$190.3856	$190.39	$190.40	$190.40
Purchase #2	$92.25	9.791%	$101.2822	$101.28	$101.30	$101.30
Purchase #3	$217.67	12.200%	$244.2257	$244.23	$244.25	$244.20
Purchase #4	$85.81	5.744%	$90.7389	$90.74	$90.75	$90.70
Purchase #5	$81.31	5.620%	$85.8796	$85.88	$85.90	$85.90
Purchase #6	$158.86	6.601%	$169.3463	$169.35	$169.35	$169.30
Purchase #7	$134.53	12.333%	$151.1216	$151.12	$151.10	$151.10
7 purchase totals =	$944.91		$1,032.9799	$1,032.99	$1,033.05	$1,032.90