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	$197.89	3.651%	$205.115	$205.12	$205.10	$205.10
Purchase #2	$180.71	3.642%	$187.2915	$187.29	$187.30	$187.30
Purchase #3	$179.31	9.636%	$196.5883	$196.59	$196.60	$196.60
Purchase #4	$203.69	5.759%	$215.4205	$215.42	$215.40	$215.40
Purchase #5	$222.29	9.331%	$243.0319	$243.03	$243.05	$243.00
Purchase #6	$220.42	11.265%	$245.2503	$245.25	$245.25	$245.30
Purchase #7	$197.81	4.499%	$206.7095	$206.71	$206.70	$206.70
7 purchase totals =	$1,402.12		$1,499.4070	$1,499.41	$1,499.40	$1,499.40