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	$45.31	3.649%	$46.9634	$46.96	$46.95	$47.00
Purchase #2	$200.79	5.743%	$212.3214	$212.32	$212.30	$212.30
Purchase #3	$62.42	5.488%	$65.8456	$65.85	$65.85	$65.80
Purchase #4	$234.29	4.145%	$244.0013	$244.00	$244.00	$244.00
Purchase #5	$52.46	13.859%	$59.7304	$59.73	$59.75	$59.70
Purchase #6	$209.76	9.146%	$228.9446	$228.94	$228.95	$228.90
Purchase #7	$197.38	10.850%	$218.7957	$218.80	$218.80	$218.80
7 purchase totals =	$1,002.41		$1,076.6024	$1,076.60	$1,076.60	$1,076.50