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	$115.85	12.251%	$130.0428	$130.04	$130.05	$130.00
Purchase #2	$83.52	7.146%	$89.4883	$89.49	$89.50	$89.50
Purchase #3	$51.66	6.332%	$54.9311	$54.93	$54.95	$54.90
Purchase #4	$5.32	7.531%	$5.7206	$5.72	$5.70	$5.70
Purchase #5	$68.34	4.589%	$71.4761	$71.48	$71.50	$71.50
Purchase #6	$168.36	8.702%	$183.0107	$183.01	$183.00	$183.00
Purchase #7	$164.77	4.769%	$172.6279	$172.63	$172.65	$172.60
7 purchase totals =	$657.82		$707.2975	$707.30	$707.35	$707.20