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	$244.78	7.593%	$263.3661	$263.37	$263.35	$263.40
Purchase #2	$32.56	3.576%	$33.7243	$33.72	$33.70	$33.70
Purchase #3	$89.93	5.383%	$94.7709	$94.77	$94.75	$94.80
Purchase #4	$103.84	6.137%	$110.2127	$110.21	$110.20	$110.20
Purchase #5	$133.80	7.388%	$143.6851	$143.69	$143.70	$143.70
Purchase #6	$249.76	9.402%	$273.2424	$273.24	$273.25	$273.20
Purchase #7	$207.61	7.362%	$222.8942	$222.89	$222.90	$222.90
7 purchase totals =	$1,062.28		$1,141.8957	$1,141.89	$1,141.85	$1,141.90