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	$220.41	7.223%	$236.3302	$236.33	$236.35	$236.30
Purchase #2	$225.31	13.387%	$255.4722	$255.47	$255.45	$255.50
Purchase #3	$25.51	7.813%	$27.5031	$27.50	$27.50	$27.50
Purchase #4	$38.64	13.410%	$43.8216	$43.82	$43.80	$43.80
Purchase #5	$164.69	6.767%	$175.8346	$175.83	$175.85	$175.80
Purchase #6	$92.45	6.481%	$98.4417	$98.44	$98.45	$98.40
Purchase #7	$99.43	11.588%	$110.9519	$110.95	$110.95	$111.00
7 purchase totals =	$866.44		$948.3553	$948.34	$948.35	$948.30