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	$52.66	3.305%	$54.4004	$54.40	$54.40	$54.40
Purchase #2	$58.31	9.364%	$63.7701	$63.77	$63.75	$63.80
Purchase #3	$190.79	13.373%	$216.3043	$216.30	$216.30	$216.30
Purchase #4	$127.88	10.276%	$141.0209	$141.02	$141.00	$141.00
Purchase #5	$237.38	7.113%	$254.2648	$254.26	$254.25	$254.30
Purchase #6	$116.27	13.850%	$132.3734	$132.37	$132.35	$132.40
Purchase #7	$240.54	5.552%	$253.8948	$253.89	$253.90	$253.90
7 purchase totals =	$1,023.83		$1,116.0287	$1,116.01	$1,115.95	$1,116.10