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	$135.95	4.318%	$141.8203	$141.82	$141.80	$141.80
Purchase #2	$112.31	4.568%	$117.4403	$117.44	$117.45	$117.40
Purchase #3	$107.50	10.781%	$119.0896	$119.09	$119.10	$119.10
Purchase #4	$216.26	11.256%	$240.6022	$240.60	$240.60	$240.60
Purchase #5	$234.33	12.345%	$263.258	$263.26	$263.25	$263.30
Purchase #6	$155.62	6.611%	$165.908	$165.91	$165.90	$165.90
Purchase #7	$54.73	8.251%	$59.2458	$59.25	$59.25	$59.20
7 purchase totals =	$1,016.70		$1,107.3642	$1,107.37	$1,107.35	$1,107.30