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	$174.58	4.540%	$182.5059	$182.51	$182.50	$182.50
Purchase #2	$28.66	8.204%	$31.0113	$31.01	$31.00	$31.00
Purchase #3	$17.94	13.133%	$20.2961	$20.30	$20.30	$20.30
Purchase #4	$106.89	13.102%	$120.8947	$120.89	$120.90	$120.90
Purchase #5	$160.74	7.115%	$172.1767	$172.18	$172.20	$172.20
Purchase #6	$209.29	10.710%	$231.705	$231.71	$231.70	$231.70
Purchase #7	$248.26	6.546%	$264.5111	$264.51	$264.50	$264.50
7 purchase totals =	$946.36		$1,023.1008	$1,023.11	$1,023.10	$1,023.10