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	$175.89	11.713%	$196.492	$196.49	$196.50	$196.50
Purchase #2	$80.55	12.349%	$90.4971	$90.50	$90.50	$90.50
Purchase #3	$175.46	3.820%	$182.1626	$182.16	$182.15	$182.20
Purchase #4	$223.52	5.310%	$235.3889	$235.39	$235.40	$235.40
Purchase #5	$197.94	13.213%	$224.0938	$224.09	$224.10	$224.10
Purchase #6	$105.54	12.841%	$119.0924	$119.09	$119.10	$119.10
Purchase #7	$232.31	9.468%	$254.3051	$254.31	$254.30	$254.30
7 purchase totals =	$1,191.21		$1,302.0319	$1,302.03	$1,302.05	$1,302.10