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	$229.67	10.438%	$253.643	$253.64	$253.65	$253.60
Purchase #2	$120.90	7.670%	$130.173	$130.17	$130.15	$130.20
Purchase #3	$139.42	8.486%	$151.2512	$151.25	$151.25	$151.30
Purchase #4	$77.86	3.174%	$80.3313	$80.33	$80.35	$80.30
Purchase #5	$197.32	7.231%	$211.5882	$211.59	$211.60	$211.60
Purchase #6	$51.67	3.214%	$53.3307	$53.33	$53.35	$53.30
Purchase #7	$168.54	6.586%	$179.64	$179.64	$179.65	$179.60
7 purchase totals =	$985.38		$1,059.9574	$1,059.95	$1,060.00	$1,059.90