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	$140.29	7.533%	$150.858	$150.86	$150.85	$150.90
Purchase #2	$33.99	9.568%	$37.2422	$37.24	$37.25	$37.20
Purchase #3	$36.83	5.606%	$38.8947	$38.89	$38.90	$38.90
Purchase #4	$44.47	8.507%	$48.2531	$48.25	$48.25	$48.30
Purchase #5	$64.25	12.430%	$72.2363	$72.24	$72.25	$72.20
Purchase #6	$198.29	13.853%	$225.7591	$225.76	$225.75	$225.80
Purchase #7	$180.41	7.662%	$194.233	$194.23	$194.25	$194.20
7 purchase totals =	$698.53		$767.4764	$767.47	$767.50	$767.50