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	$167.82	3.797%	$174.1921	$174.19	$174.20	$174.20
Purchase #2	$178.48	7.283%	$191.4787	$191.48	$191.50	$191.50
Purchase #3	$190.87	3.416%	$197.3901	$197.39	$197.40	$197.40
Purchase #4	$42.36	6.245%	$45.0054	$45.01	$45.00	$45.00
Purchase #5	$184.58	13.174%	$208.8966	$208.90	$208.90	$208.90
Purchase #6	$56.75	8.172%	$61.3876	$61.39	$61.40	$61.40
Purchase #7	$181.38	8.374%	$196.5688	$196.57	$196.55	$196.60
7 purchase totals =	$1,002.24		$1,074.9193	$1,074.93	$1,074.95	$1,075.00