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	$43.43	3.320%	$44.8719	$44.87	$44.85	$44.90
Purchase #2	$178.72	3.406%	$184.8072	$184.81	$184.80	$184.80
Purchase #3	$37.89	11.349%	$42.1901	$42.19	$42.20	$42.20
Purchase #4	$59.97	9.733%	$65.8069	$65.81	$65.80	$65.80
Purchase #5	$213.89	7.339%	$229.5874	$229.59	$229.60	$229.60
Purchase #6	$187.66	12.472%	$211.065	$211.07	$211.05	$211.10
Purchase #7	$169.55	11.150%	$188.4548	$188.45	$188.45	$188.50
7 purchase totals =	$891.11		$966.7833	$966.79	$966.75	$966.90