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	$201.70	5.379%	$212.5494	$212.55	$212.55	$212.50
Purchase #2	$66.30	7.560%	$71.3123	$71.31	$71.30	$71.30
Purchase #3	$127.87	12.301%	$143.5993	$143.60	$143.60	$143.60
Purchase #4	$205.57	5.365%	$216.5988	$216.60	$216.60	$216.60
Purchase #5	$192.88	13.439%	$218.8011	$218.80	$218.80	$218.80
Purchase #6	$190.73	9.340%	$208.5442	$208.54	$208.55	$208.50
Purchase #7	$35.39	4.809%	$37.0919	$37.09	$37.10	$37.10
7 purchase totals =	$1,020.44		$1,108.4970	$1,108.49	$1,108.50	$1,108.40