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	$38.96	13.791%	$44.333	$44.33	$44.35	$44.30
Purchase #2	$70.86	6.847%	$75.7118	$75.71	$75.70	$75.70
Purchase #3	$248.30	6.854%	$265.3185	$265.32	$265.30	$265.30
Purchase #4	$198.27	3.304%	$204.8208	$204.82	$204.80	$204.80
Purchase #5	$78.59	5.854%	$83.1907	$83.19	$83.20	$83.20
Purchase #6	$124.30	6.515%	$132.3981	$132.40	$132.40	$132.40
Purchase #7	$196.38	7.205%	$210.5292	$210.53	$210.55	$210.50
7 purchase totals =	$955.66		$1,016.3021	$1,016.30	$1,016.30	$1,016.20