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	$186.67	5.133%	$196.2518	$196.25	$196.25	$196.30
Purchase #2	$31.63	13.461%	$35.8877	$35.89	$35.90	$35.90
Purchase #3	$205.65	6.245%	$218.4928	$218.49	$218.50	$218.50
Purchase #4	$65.73	9.530%	$71.9941	$71.99	$72.00	$72.00
Purchase #5	$132.55	9.689%	$145.3928	$145.39	$145.40	$145.40
Purchase #6	$34.41	7.345%	$36.9374	$36.94	$36.95	$36.90
Purchase #7	$245.90	5.504%	$259.4343	$259.43	$259.45	$259.40
7 purchase totals =	$902.54		$964.3909	$964.38	$964.45	$964.40