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	$215.84	13.758%	$245.5353	$245.54	$245.55	$245.50
Purchase #2	$197.90	4.327%	$206.4631	$206.46	$206.45	$206.50
Purchase #3	$100.37	4.400%	$104.7863	$104.79	$104.80	$104.80
Purchase #4	$25.55	11.136%	$28.3952	$28.40	$28.40	$28.40
Purchase #5	$146.95	9.361%	$160.706	$160.71	$160.70	$160.70
Purchase #6	$196.67	13.330%	$222.8861	$222.89	$222.90	$222.90
Purchase #7	$207.47	4.284%	$216.358	$216.36	$216.35	$216.40
7 purchase totals =	$1,090.75		$1,185.1300	$1,185.15	$1,185.15	$1,185.20