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	$175.76	11.535%	$196.0339	$196.03	$196.05	$196.00
Purchase #2	$72.51	11.763%	$81.0394	$81.04	$81.05	$81.00
Purchase #3	$47.46	9.438%	$51.9393	$51.94	$51.95	$51.90
Purchase #4	$75.96	12.282%	$85.2894	$85.29	$85.30	$85.30
Purchase #5	$225.91	8.326%	$244.7193	$244.72	$244.70	$244.70
Purchase #6	$233.39	10.604%	$258.1387	$258.14	$258.15	$258.10
Purchase #7	$243.28	3.342%	$251.4104	$251.41	$251.40	$251.40
7 purchase totals =	$1,074.27		$1,168.5704	$1,168.57	$1,168.60	$1,168.40