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	$198.50	6.324%	$211.0531	$211.05	$211.05	$211.10
Purchase #2	$171.97	8.243%	$186.1455	$186.15	$186.15	$186.10
Purchase #3	$25.73	3.598%	$26.6558	$26.66	$26.65	$26.70
Purchase #4	$219.25	11.344%	$244.1217	$244.12	$244.10	$244.10
Purchase #5	$234.32	13.495%	$265.9415	$265.94	$265.95	$265.90
Purchase #6	$69.53	13.494%	$78.9124	$78.91	$78.90	$78.90
Purchase #7	$34.72	8.113%	$37.5368	$37.54	$37.55	$37.50
7 purchase totals =	$954.02		$1,050.3668	$1,050.37	$1,050.35	$1,050.30