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	$88.50	4.858%	$92.7993	$92.80	$92.80	$92.80
Purchase #2	$156.57	5.731%	$165.543	$165.54	$165.55	$165.50
Purchase #3	$125.51	9.857%	$137.8815	$137.88	$137.90	$137.90
Purchase #4	$243.85	7.282%	$261.6072	$261.61	$261.60	$261.60
Purchase #5	$136.69	11.379%	$152.244	$152.24	$152.25	$152.20
Purchase #6	$129.93	7.274%	$139.3811	$139.38	$139.40	$139.40
Purchase #7	$66.48	9.685%	$72.9186	$72.92	$72.90	$72.90
7 purchase totals =	$947.53		$1,022.3747	$1,022.37	$1,022.40	$1,022.30