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	$219.41	10.258%	$241.9171	$241.92	$241.90	$241.90
Purchase #2	$20.30	7.831%	$21.8897	$21.89	$21.90	$21.90
Purchase #3	$9.61	7.234%	$10.3052	$10.31	$10.30	$10.30
Purchase #4	$154.94	4.647%	$162.1401	$162.14	$162.15	$162.10
Purchase #5	$199.72	3.709%	$207.1276	$207.13	$207.15	$207.10
Purchase #6	$245.35	3.325%	$253.5079	$253.51	$253.50	$253.50
Purchase #7	$240.36	10.324%	$265.1748	$265.17	$265.15	$265.20
7 purchase totals =	$1,089.69		$1,162.0624	$1,162.07	$1,162.05	$1,162.00