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	$209.32	4.625%	$219.0011	$219.00	$219.00	$219.00
Purchase #2	$165.83	5.362%	$174.7218	$174.72	$174.70	$174.70
Purchase #3	$156.31	12.160%	$175.3173	$175.32	$175.30	$175.30
Purchase #4	$208.48	3.754%	$216.3063	$216.31	$216.30	$216.30
Purchase #5	$110.81	12.607%	$124.7798	$124.78	$124.80	$124.80
Purchase #6	$112.56	13.205%	$127.4235	$127.42	$127.40	$127.40
Purchase #7	$105.65	6.517%	$112.5352	$112.54	$112.55	$112.50
7 purchase totals =	$1,068.96		$1,150.0850	$1,150.09	$1,150.05	$1,150.00