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	$194.67	7.473%	$209.2177	$209.22	$209.20	$209.20
Purchase #2	$168.57	6.475%	$179.4849	$179.48	$179.50	$179.50
Purchase #3	$166.43	4.158%	$173.3502	$173.35	$173.35	$173.40
Purchase #4	$69.72	9.197%	$76.1321	$76.13	$76.15	$76.10
Purchase #5	$68.69	4.567%	$71.8271	$71.83	$71.85	$71.80
Purchase #6	$184.27	6.477%	$196.2052	$196.21	$196.20	$196.20
Purchase #7	$156.51	7.780%	$168.6865	$168.69	$168.70	$168.70
7 purchase totals =	$1,008.86		$1,074.9037	$1,074.91	$1,074.95	$1,074.90