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	$132.43	7.283%	$142.0749	$142.07	$142.05	$142.10
Purchase #2	$28.53	6.301%	$30.3277	$30.33	$30.35	$30.30
Purchase #3	$98.73	11.305%	$109.8914	$109.89	$109.90	$109.90
Purchase #4	$211.55	3.442%	$218.8316	$218.83	$218.85	$218.80
Purchase #5	$28.27	11.178%	$31.43	$31.43	$31.45	$31.40
Purchase #6	$101.63	3.338%	$105.0224	$105.02	$105.00	$105.00
Purchase #7	$83.71	5.408%	$88.237	$88.24	$88.25	$88.20
7 purchase totals =	$684.85		$725.8150	$725.81	$725.85	$725.70