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	$146.95	13.855%	$167.3099	$167.31	$167.30	$167.30
Purchase #2	$197.45	13.194%	$223.5016	$223.50	$223.50	$223.50
Purchase #3	$57.49	3.552%	$59.532	$59.53	$59.55	$59.50
Purchase #4	$238.53	4.136%	$248.3956	$248.40	$248.40	$248.40
Purchase #5	$136.84	13.515%	$155.3339	$155.33	$155.35	$155.30
Purchase #6	$223.59	11.644%	$249.6248	$249.62	$249.60	$249.60
Purchase #7	$36.52	7.273%	$39.1761	$39.18	$39.20	$39.20
7 purchase totals =	$1,037.37		$1,142.8739	$1,142.87	$1,142.90	$1,142.80