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	$223.41	3.503%	$231.2361	$231.24	$231.25	$231.20
Purchase #2	$76.28	3.197%	$78.7187	$78.72	$78.70	$78.70
Purchase #3	$64.49	4.781%	$67.5733	$67.57	$67.55	$67.60
Purchase #4	$146.63	11.312%	$163.2168	$163.22	$163.20	$163.20
Purchase #5	$154.60	7.142%	$165.6415	$165.64	$165.65	$165.60
Purchase #6	$188.40	9.281%	$205.8854	$205.89	$205.90	$205.90
Purchase #7	$97.81	4.566%	$102.276	$102.28	$102.30	$102.30
7 purchase totals =	$951.62		$1,014.5478	$1,014.56	$1,014.55	$1,014.50