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	$212.50	5.469%	$224.1216	$224.12	$224.10	$224.10
Purchase #2	$62.71	13.298%	$71.0492	$71.05	$71.05	$71.00
Purchase #3	$143.86	4.519%	$150.361	$150.36	$150.35	$150.40
Purchase #4	$74.93	4.742%	$78.4832	$78.48	$78.50	$78.50
Purchase #5	$221.57	10.112%	$243.9752	$243.98	$244.00	$244.00
Purchase #6	$136.55	13.243%	$154.6333	$154.63	$154.65	$154.60
Purchase #7	$141.36	11.574%	$157.721	$157.72	$157.70	$157.70
7 purchase totals =	$993.48		$1,080.3445	$1,080.34	$1,080.35	$1,080.30