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	$78.44	12.155%	$87.9744	$87.97	$87.95	$88.00
Purchase #2	$55.34	6.619%	$59.003	$59.00	$59.00	$59.00
Purchase #3	$196.27	4.305%	$204.7194	$204.72	$204.70	$204.70
Purchase #4	$223.89	8.649%	$243.2542	$243.25	$243.25	$243.30
Purchase #5	$113.53	12.167%	$127.3432	$127.34	$127.35	$127.30
Purchase #6	$147.79	12.601%	$166.413	$166.41	$166.40	$166.40
Purchase #7	$132.59	10.520%	$146.5385	$146.54	$146.55	$146.50
7 purchase totals =	$947.85		$1,035.2457	$1,035.23	$1,035.20	$1,035.20