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	$98.29	7.165%	$105.3325	$105.33	$105.35	$105.30
Purchase #2	$162.47	7.815%	$175.167	$175.17	$175.15	$175.20
Purchase #3	$83.33	10.438%	$92.028	$92.03	$92.05	$92.00
Purchase #4	$179.86	7.661%	$193.6391	$193.64	$193.65	$193.60
Purchase #5	$211.79	5.323%	$223.0636	$223.06	$223.05	$223.10
Purchase #6	$76.88	11.720%	$85.8903	$85.89	$85.90	$85.90
Purchase #7	$40.66	7.222%	$43.5965	$43.60	$43.60	$43.60
7 purchase totals =	$853.28		$918.7170	$918.72	$918.75	$918.70