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	$69.94	3.833%	$72.6208	$72.62	$72.60	$72.60
Purchase #2	$83.42	5.815%	$88.2709	$88.27	$88.25	$88.30
Purchase #3	$170.71	6.787%	$182.2961	$182.30	$182.30	$182.30
Purchase #4	$79.57	3.583%	$82.421	$82.42	$82.40	$82.40
Purchase #5	$169.95	3.175%	$175.3459	$175.35	$175.35	$175.30
Purchase #6	$50.49	7.596%	$54.3252	$54.33	$54.35	$54.30
Purchase #7	$51.72	12.499%	$58.1845	$58.18	$58.20	$58.20
7 purchase totals =	$675.80		$713.4644	$713.47	$713.45	$713.40