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	$224.59	13.363%	$254.602	$254.60	$254.60	$254.60
Purchase #2	$5.63	11.350%	$6.269	$6.27	$6.25	$6.30
Purchase #3	$250.30	11.139%	$278.1809	$278.18	$278.20	$278.20
Purchase #4	$191.50	12.509%	$215.4547	$215.45	$215.45	$215.50
Purchase #5	$129.57	8.388%	$140.4383	$140.44	$140.45	$140.40
Purchase #6	$55.32	11.331%	$61.5883	$61.59	$61.60	$61.60
Purchase #7	$55.28	12.761%	$62.3343	$62.33	$62.35	$62.30
7 purchase totals =	$912.19		$1,018.8675	$1,018.86	$1,018.90	$1,018.90