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	$119.75	8.628%	$130.082	$130.08	$130.10	$130.10
Purchase #2	$126.31	10.195%	$139.1873	$139.19	$139.20	$139.20
Purchase #3	$87.27	13.818%	$99.329	$99.33	$99.35	$99.30
Purchase #4	$33.35	11.174%	$37.0765	$37.08	$37.10	$37.10
Purchase #5	$189.56	5.741%	$200.4426	$200.44	$200.45	$200.40
Purchase #6	$39.93	11.117%	$44.369	$44.37	$44.35	$44.40
Purchase #7	$221.69	10.570%	$245.1226	$245.12	$245.10	$245.10
7 purchase totals =	$817.86		$895.6090	$895.61	$895.65	$895.60