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	$112.50	9.384%	$123.057	$123.06	$123.05	$123.10
Purchase #2	$70.82	4.322%	$73.8808	$73.88	$73.90	$73.90
Purchase #3	$86.92	3.125%	$89.6363	$89.64	$89.65	$89.60
Purchase #4	$175.53	5.834%	$185.7704	$185.77	$185.75	$185.80
Purchase #5	$233.73	3.530%	$241.9807	$241.98	$242.00	$242.00
Purchase #6	$243.90	12.312%	$273.929	$273.93	$273.95	$273.90
Purchase #7	$37.33	13.167%	$42.2452	$42.25	$42.25	$42.20
7 purchase totals =	$960.73		$1,030.4994	$1,030.51	$1,030.55	$1,030.50