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	$127.89	3.174%	$131.9492	$131.95	$131.95	$131.90
Purchase #2	$191.62	3.622%	$198.5605	$198.56	$198.55	$198.60
Purchase #3	$145.62	11.626%	$162.5498	$162.55	$162.55	$162.50
Purchase #4	$76.79	13.811%	$87.3955	$87.40	$87.40	$87.40
Purchase #5	$21.94	4.263%	$22.8753	$22.88	$22.90	$22.90
Purchase #6	$188.29	12.180%	$211.2237	$211.22	$211.20	$211.20
Purchase #7	$172.58	13.800%	$196.396	$196.40	$196.40	$196.40
7 purchase totals =	$924.73		$1,010.9500	$1,010.96	$1,010.95	$1,010.90