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	$163.90	5.465%	$172.8571	$172.86	$172.85	$172.90
Purchase #2	$55.98	5.755%	$59.2016	$59.20	$59.20	$59.20
Purchase #3	$64.42	10.604%	$71.2511	$71.25	$71.25	$71.30
Purchase #4	$18.77	13.443%	$21.2933	$21.29	$21.30	$21.30
Purchase #5	$35.31	6.681%	$37.6691	$37.67	$37.65	$37.70
Purchase #6	$205.47	4.844%	$215.423	$215.42	$215.40	$215.40
Purchase #7	$139.36	6.310%	$148.1536	$148.15	$148.15	$148.20
7 purchase totals =	$683.21		$725.8488	$725.84	$725.80	$726.00