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	$190.94	5.478%	$201.3997	$201.40	$201.40	$201.40
Purchase #2	$55.46	6.711%	$59.1819	$59.18	$59.20	$59.20
Purchase #3	$5.83	9.791%	$6.4008	$6.40	$6.40	$6.40
Purchase #4	$111.41	11.252%	$123.9459	$123.95	$123.95	$123.90
Purchase #5	$167.88	13.686%	$190.8561	$190.86	$190.85	$190.90
Purchase #6	$153.63	8.854%	$167.2324	$167.23	$167.25	$167.20
Purchase #7	$165.68	6.666%	$176.7242	$176.72	$176.70	$176.70
7 purchase totals =	$850.83		$925.7410	$925.74	$925.75	$925.70