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	$120.85	4.791%	$126.6399	$126.64	$126.65	$126.60
Purchase #2	$191.89	10.304%	$211.6623	$211.66	$211.65	$211.70
Purchase #3	$113.56	6.175%	$120.5723	$120.57	$120.55	$120.60
Purchase #4	$57.35	3.372%	$59.2838	$59.28	$59.30	$59.30
Purchase #5	$243.50	13.556%	$276.5089	$276.51	$276.50	$276.50
Purchase #6	$161.61	11.698%	$180.5151	$180.52	$180.50	$180.50
Purchase #7	$74.45	4.848%	$78.0593	$78.06	$78.05	$78.10
7 purchase totals =	$963.21		$1,053.2416	$1,053.24	$1,053.20	$1,053.30