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	$222.86	3.731%	$231.1749	$231.17	$231.15	$231.20
Purchase #2	$36.32	4.469%	$37.9431	$37.94	$37.95	$37.90
Purchase #3	$230.84	4.511%	$241.2532	$241.25	$241.25	$241.30
Purchase #4	$199.71	7.595%	$214.878	$214.88	$214.90	$214.90
Purchase #5	$96.29	6.751%	$102.7905	$102.79	$102.80	$102.80
Purchase #6	$98.72	8.718%	$107.3264	$107.33	$107.35	$107.30
Purchase #7	$162.82	6.844%	$173.9634	$173.96	$173.95	$174.00
7 purchase totals =	$1,047.56		$1,109.3295	$1,109.32	$1,109.35	$1,109.40