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	$186.72	11.867%	$208.8781	$208.88	$208.90	$208.90
Purchase #2	$67.43	8.141%	$72.9195	$72.92	$72.90	$72.90
Purchase #3	$217.79	13.294%	$246.743	$246.74	$246.75	$246.70
Purchase #4	$38.29	11.742%	$42.786	$42.79	$42.80	$42.80
Purchase #5	$203.39	6.740%	$217.0985	$217.10	$217.10	$217.10
Purchase #6	$161.67	5.815%	$171.0711	$171.07	$171.05	$171.10
Purchase #7	$97.43	4.763%	$102.0706	$102.07	$102.05	$102.10
7 purchase totals =	$972.72		$1,061.5668	$1,061.57	$1,061.55	$1,061.60