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	$105.26	7.764%	$113.4324	$113.43	$113.45	$113.40
Purchase #2	$244.39	7.846%	$263.5648	$263.56	$263.55	$263.60
Purchase #3	$91.65	7.572%	$98.5897	$98.59	$98.60	$98.60
Purchase #4	$124.75	7.757%	$134.4269	$134.43	$134.45	$134.40
Purchase #5	$124.41	13.723%	$141.4828	$141.48	$141.50	$141.50
Purchase #6	$207.95	10.546%	$229.8804	$229.88	$229.90	$229.90
Purchase #7	$212.89	13.482%	$241.5918	$241.59	$241.60	$241.60
7 purchase totals =	$1,111.30		$1,222.9688	$1,222.96	$1,223.05	$1,223.00