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	$13.38	8.631%	$14.5348	$14.53	$14.55	$14.50
Purchase #2	$114.92	12.256%	$129.0046	$129.00	$129.00	$129.00
Purchase #3	$32.79	13.131%	$37.0957	$37.10	$37.10	$37.10
Purchase #4	$88.62	13.406%	$100.5004	$100.50	$100.50	$100.50
Purchase #5	$170.57	6.799%	$182.1671	$182.17	$182.15	$182.20
Purchase #6	$191.45	11.481%	$213.4304	$213.43	$213.45	$213.40
Purchase #7	$94.86	8.639%	$103.055	$103.06	$103.05	$103.10
7 purchase totals =	$706.59		$779.7880	$779.79	$779.80	$779.80