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	$107.26	5.454%	$113.11	$113.11	$113.10	$113.10
Purchase #2	$7.56	3.355%	$7.8136	$7.81	$7.80	$7.80
Purchase #3	$230.51	6.232%	$244.8754	$244.88	$244.90	$244.90
Purchase #4	$214.30	4.274%	$223.4592	$223.46	$223.45	$223.50
Purchase #5	$148.94	12.865%	$168.1011	$168.10	$168.10	$168.10
Purchase #6	$52.35	12.817%	$59.0597	$59.06	$59.05	$59.10
Purchase #7	$245.38	6.787%	$262.0339	$262.03	$262.05	$262.00
7 purchase totals =	$1,006.30		$1,078.4529	$1,078.45	$1,078.45	$1,078.50