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	$200.80	7.615%	$216.0909	$216.09	$216.10	$216.10
Purchase #2	$219.70	4.346%	$229.2482	$229.25	$229.25	$229.20
Purchase #3	$101.96	9.427%	$111.5718	$111.57	$111.55	$111.60
Purchase #4	$230.29	4.261%	$240.1027	$240.10	$240.10	$240.10
Purchase #5	$96.48	10.214%	$106.3345	$106.33	$106.35	$106.30
Purchase #6	$64.60	9.316%	$70.6181	$70.62	$70.60	$70.60
Purchase #7	$36.69	10.620%	$40.5865	$40.59	$40.60	$40.60
7 purchase totals =	$950.52		$1,014.5527	$1,014.55	$1,014.55	$1,014.50