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	$7.49	6.195%	$7.954	$7.95	$7.95	$8.00
Purchase #2	$75.93	3.471%	$78.5655	$78.57	$78.55	$78.60
Purchase #3	$173.31	9.263%	$189.3637	$189.36	$189.35	$189.40
Purchase #4	$235.27	4.619%	$246.1371	$246.14	$246.15	$246.10
Purchase #5	$63.54	6.197%	$67.4776	$67.48	$67.50	$67.50
Purchase #6	$147.36	13.628%	$167.4422	$167.44	$167.45	$167.40
Purchase #7	$241.91	7.494%	$260.0387	$260.04	$260.05	$260.00
7 purchase totals =	$944.81		$1,016.9788	$1,016.98	$1,017.00	$1,017.00