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	$235.31	4.216%	$245.2307	$245.23	$245.25	$245.20
Purchase #2	$130.69	13.599%	$148.4625	$148.46	$148.45	$148.50
Purchase #3	$161.92	4.666%	$169.4752	$169.48	$169.50	$169.50
Purchase #4	$158.96	6.724%	$169.6485	$169.65	$169.65	$169.60
Purchase #5	$76.64	6.350%	$81.5066	$81.51	$81.50	$81.50
Purchase #6	$242.43	13.655%	$275.5338	$275.53	$275.55	$275.50
Purchase #7	$55.28	7.617%	$59.4907	$59.49	$59.50	$59.50
7 purchase totals =	$1,061.23		$1,149.3480	$1,149.35	$1,149.40	$1,149.30