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	$98.29	7.545%	$105.706	$105.71	$105.70	$105.70
Purchase #2	$127.35	7.621%	$137.0553	$137.06	$137.05	$137.10
Purchase #3	$145.43	9.849%	$159.7534	$159.75	$159.75	$159.80
Purchase #4	$134.77	7.668%	$145.1042	$145.10	$145.10	$145.10
Purchase #5	$52.36	10.574%	$57.8965	$57.90	$57.90	$57.90
Purchase #6	$89.31	8.165%	$96.6022	$96.60	$96.60	$96.60
Purchase #7	$56.95	13.281%	$64.5135	$64.51	$64.50	$64.50
7 purchase totals =	$704.46		$766.6311	$766.63	$766.60	$766.70