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	$207.72	11.665%	$231.9505	$231.95	$231.95	$232.00
Purchase #2	$87.47	8.641%	$95.0283	$95.03	$95.05	$95.00
Purchase #3	$85.44	6.334%	$90.8518	$90.85	$90.85	$90.90
Purchase #4	$149.38	8.185%	$161.6068	$161.61	$161.60	$161.60
Purchase #5	$191.70	9.579%	$210.0629	$210.06	$210.05	$210.10
Purchase #6	$81.94	9.673%	$89.8661	$89.87	$89.85	$89.90
Purchase #7	$245.56	6.753%	$262.1427	$262.14	$262.15	$262.10
7 purchase totals =	$1,049.21		$1,141.5091	$1,141.51	$1,141.50	$1,141.60