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	$187.89	10.501%	$207.6203	$207.62	$207.60	$207.60
Purchase #2	$225.39	4.455%	$235.4311	$235.43	$235.45	$235.40
Purchase #3	$44.98	5.841%	$47.6073	$47.61	$47.60	$47.60
Purchase #4	$237.88	5.469%	$250.8897	$250.89	$250.90	$250.90
Purchase #5	$104.47	6.690%	$111.459	$111.46	$111.45	$111.50
Purchase #6	$151.34	10.219%	$166.8054	$166.81	$166.80	$166.80
Purchase #7	$105.56	4.175%	$109.9671	$109.97	$109.95	$110.00
7 purchase totals =	$1,057.51		$1,129.7799	$1,129.79	$1,129.75	$1,129.80