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	$74.44	3.341%	$76.927	$76.93	$76.95	$76.90
Purchase #2	$53.36	5.118%	$56.091	$56.09	$56.10	$56.10
Purchase #3	$134.46	6.765%	$143.5562	$143.56	$143.55	$143.60
Purchase #4	$135.90	9.588%	$148.9301	$148.93	$148.95	$148.90
Purchase #5	$218.87	10.238%	$241.2779	$241.28	$241.30	$241.30
Purchase #6	$215.69	13.844%	$245.5501	$245.55	$245.55	$245.60
Purchase #7	$149.31	13.524%	$169.5027	$169.50	$169.50	$169.50
7 purchase totals =	$982.03		$1,081.8350	$1,081.84	$1,081.90	$1,081.90