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	$174.96	13.199%	$198.053	$198.05	$198.05	$198.10
Purchase #2	$226.96	13.507%	$257.6155	$257.62	$257.60	$257.60
Purchase #3	$196.70	6.832%	$210.1385	$210.14	$210.15	$210.10
Purchase #4	$57.46	3.191%	$59.2935	$59.29	$59.30	$59.30
Purchase #5	$116.47	13.410%	$132.0886	$132.09	$132.10	$132.10
Purchase #6	$240.46	11.772%	$268.767	$268.77	$268.75	$268.80
Purchase #7	$63.51	11.513%	$70.8219	$70.82	$70.80	$70.80
7 purchase totals =	$1,076.52		$1,196.7780	$1,196.78	$1,196.75	$1,196.80