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	$176.36	11.676%	$196.9518	$196.95	$196.95	$197.00
Purchase #2	$223.78	13.309%	$253.5629	$253.56	$253.55	$253.60
Purchase #3	$79.97	12.186%	$89.7151	$89.72	$89.70	$89.70
Purchase #4	$118.50	12.517%	$133.3326	$133.33	$133.35	$133.30
Purchase #5	$34.72	10.456%	$38.3503	$38.35	$38.35	$38.40
Purchase #6	$82.89	12.471%	$93.2272	$93.23	$93.25	$93.20
Purchase #7	$213.78	11.444%	$238.245	$238.25	$238.25	$238.20
7 purchase totals =	$930.00		$1,043.3849	$1,043.39	$1,043.40	$1,043.40